rustpkg: Do not guess version if not given

rustpkg accessed git repo to read tags and guess package version,
but it's not quite useful: version can be given explicitly by user,
and implicit guess may cause confusions.
rustpkg::version: Remove enum Version

Currently rustpkg doesn't use SemanticVersion or Tagged, so they are
removed. Remaining variants are replaced by `Option<~str>`.
rustpkg: Compute hash to find crate

Previously rustpkg tried to parse filenames to find crate. Now ue use
deterministic hashes, so it becomes possible to directly construct
filename and check if the file exists.
rustpkg::crate_id: Remove CrateId

There is no significant difference between `rustpkg::crate_id::CrateId`
and `syntax::crateid::CrateId`. rustpkg's one is replaced by syntax's
one.
Add std::os::self_exe_name()
Set LD_LIBRARY_PATH on linux for c-dynamic-dylib test

Else, libfoo can't find libcfoo.so.

bar has an rpath, which lets it find libfoo.  But libfoo doesn't have an
rapth that tells it where to find libcfoo
Follow symlinks in sysroot

Before this commit, rustc looked in `dirname $0`/../lib for libraries
but that doesn't work when rustc is invoked through a symlink.

This commit makes rustc look in `dirname $(readlink $0)`/../lib, i.e.
it first canonicalizes the symlink before walking up the directory tree.

Fixes #3632.
Make check-summary.py support file globbing

Fixes the following error when executing `make check-lite`:

    Traceback (most recent call last):
      File "/home/bnoordhuis/src/rust/src/etc/check-summary.py", line 27, in <module>
        map(summarise, logfiles)
      File "/home/bnoordhuis/src/rust/src/etc/check-summary.py", line 10, in summarise
        with open(fname) as fd:
    IOError: [Errno 2] No such file or directory: 'tmp/*.log'
Fix typo in tutorial
Redo exported macro serialization

The old method of serializing the AST gives totally bogus spans if the
expansion of an imported macro causes compilation errors. The best
solution seems to be to serialize the actual textual macro definition
and load it the same way the std-macros are. I'm not totally confident
that getting the source from the CodeMap will always do the right thing,
but it seems to work in simple cases.
Make some borrow checker errors more user friendly

A mutable and immutable borrow place some restrictions on what you can
with the variable until the borrow ends. This commit attempts to convey
to the user what those restrictions are. Also, if the original borrow is
a mutable borrow, the error message has been changed (more specifically,
i. "cannot borrow `x` as immutable because it is also borrowed as
mutable" and ii. "cannot borrow `x` as mutable more than once" have
been changed to "cannot borrow `x` because it is already borrowed as
mutable").

In addition, this adds a (custom) span note to communicate where the
original borrow ends.
Rename Invert to Flip - Issue 10632

Renamed the invert() function in iter.rs to flip().

Also renamed the Invert<T> type to Flip<T>.

Some related code comments changed. Documentation that I could find has
been updated, and all the instances I could locate where the
function/type were called have been updated as well.
Update flip() to be rev().

Consensus leaned in favour of using rev instead of flip.
Make docs search results URL-addressable

This change adds two improvements to docs searching functionality.

First, search results will immediately be displayed when a ?search=searchterm
query string parameter is provided to any docs url.

Second, search results are now inserted into the browser history, allowing for
easier navigation between search results and docs pages.
auto merge of #11478 : klutzy/rust/rustpkg-crate-id, r=cmr

This patchset consists of three parts:

- rustpkg doesn't guess crate version if it is not given by user.
- `rustpkg::version::Version` is replaced by `Option<~str>`.
  It removes some semantic versioning portions which is not currently used.
  (cc #8405 and #11396)
  `rustpkg::crate_id::CrateId` is also replaced by `syntax::crateid::CrateId`.
- rustpkg now computes hash to find crate, instead of manual filename parse.

cc @metajack
auto merge of #11686 : mankyKitty/rust/rename-invert-to-flip-issue-10632, r=alexcrichton

Renamed the ```invert()``` function in ```iter.rs``` to ```flip()```, from #10632 

Also renamed the ```Invert<T>``` type to ```Flip<T>```.

Some related code comments changed. Documentation that I could find has
been updated, and all the instances I could locate where the
function/type were called have been updated as well.

This is my first contribution to Rust! Apologies in advance if I've snarfed the 
PR process, I'm not used to rebase.

I initially had issues with the ```codegen``` section of the tests failing, however
the ```make check``` process is not reporting any failures at this time. I think
that was a local env issue more than me facerolling my changes. :)
auto merge of #11718 : ktt3ja/rust/borrowck-error-msg, r=brson

A mutable and immutable borrow place some restrictions on what you can
with the variable until the borrow ends. This commit attempts to convey
to the user what those restrictions are. Also, if the original borrow is
a mutable borrow, the error message has been changed (more specifically,
i. "cannot borrow `x` as immutable because it is also borrowed as
mutable" and ii. "cannot borrow `x` as mutable more than once" have
been changed to "cannot borrow `x` because it is already borrowed as
mutable").

In addition, this adds a (custom) span note to communicate where the
original borrow ends.

```rust
fn main() {
    match true {
        true => {
            let mut x = 1;
            let y = &x;
            let z = &mut x;
        }
        false => ()
    }
}

test.rs:6:21: 6:27 error: cannot borrow `x` as mutable because it is already borrowed as immutable
test.rs:6             let z = &mut x;
                              ^~~~~~
test.rs:5:21: 5:23 note: previous borrow of `x` occurs here; the immutable borrow prevents subsequent moves or mutable borrows of `x` until the borrow ends
test.rs:5             let y = &x;
                              ^~
test.rs:7:10: 7:10 note: previous borrow ends here
test.rs:3         true => {
test.rs:4             let mut x = 1;
test.rs:5             let y = &x;
test.rs:6             let z = &mut x;
test.rs:7         }
                  ^
```

```rust
fn foo3(t0: &mut &mut int) {
    let t1 = &mut *t0;
    let p: &int = &**t0;
}

fn main() {}

test.rs:3:19: 3:24 error: cannot borrow `**t0` because it is already borrowed as mutable
test.rs:3     let p: &int = &**t0;
                            ^~~~~
test.rs:2:14: 2:22 note: previous borrow of `**t0` as mutable occurs here; the mutable borrow prevents subsequent moves, borrows, or modification of `**t0` until the borrow ends
test.rs:2     let t1 = &mut *t0;
                       ^~~~~~~~
test.rs:4:2: 4:2 note: previous borrow ends here
test.rs:1 fn foo3(t0: &mut &mut int) {
test.rs:2     let t1 = &mut *t0;
test.rs:3     let p: &int = &**t0;
test.rs:4 }
          ^
```

For the "previous borrow ends here" note, if the span is too long (has too many lines), then only the first and last lines are printed, and the middle is replaced with dot dot dot:
```rust
fn foo3(t0: &mut &mut int) {
    let t1 = &mut *t0;
    let p: &int = &**t0;



}

fn main() {}

test.rs:3:19: 3:24 error: cannot borrow `**t0` because it is already borrowed as mutable
test.rs:3     let p: &int = &**t0;
                            ^~~~~
test.rs:2:14: 2:22 note: previous borrow of `**t0` as mutable occurs here; the mutable borrow prevents subsequent moves, borrows, or modification of `**t0` until the borrow ends
test.rs:2     let t1 = &mut *t0;
                       ^~~~~~~~
test.rs:7:2: 7:2 note: previous borrow ends here
test.rs:1 fn foo3(t0: &mut &mut int) {
...
test.rs:7 }
          ^
```

(Sidenote: the `span_end_note` currently also has issue #11715)
auto merge of #11720 : sfackler/rust/macro-export-source, r=alexcrichton

The old method of serializing the AST gives totally bogus spans if the
expansion of an imported macro causes compilation errors. The best
solution seems to be to serialize the actual textual macro definition
and load it the same way the std-macros are. I'm not totally confident
that getting the source from the CodeMap will always do the right thing,
but it seems to work in simple cases.
auto merge of #11742 : eminence/rust/dylib-test-fix, r=alexcrichton

On my Gentoo Linux machine, the c-dynamic-dylib test is failing, because libcfoo can't be found.  bar has a correct rpath for finding libfoo.so, but libfoo.so's rpath doesn't contain the right entries for finding libcfoo.


Below is the test failure on my machine.  This test pass with this commit:

```
maketest: c-dynamic-dylib
----- /storage/home/achin/devel/rust/src/test/run-make/c-dynamic-dylib/ --------------------
------ stdout ---------------------------------------------
make[1]: Entering directory `/storage/home/achin/devel/rust/src/test/run-make/c-dynamic-dylib'
gcc -Wall -Werror -g -fPIC -m64 -L /storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib -c -o /storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib/libcfoo.o cfoo.c
gcc -Wall -Werror -g -fPIC -m64 -L /storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib -o /storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib/libcfoo.so /storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib/libcfoo.o -shared
/storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/stage2/bin/rustc --out-dir /storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib -L /storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib foo.rs
/storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/stage2/bin/rustc --out-dir /storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib -L /storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib bar.rs
/storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib/bar
rm /storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib/libcfoo.o
make[1]: Leaving directory `/storage/home/achin/devel/rust/src/test/run-make/c-dynamic-dylib'

------ stderr ---------------------------------------------
/storage/home/achin/devel/rust/x86_64-unknown-linux-gnu/test/run-make/c-dynamic-dylib/bar: error while loading shared libraries: libcfoo.so: cannot open shared object file: No such file or directory
make[1]: *** [all] Error 127

------        ---------------------------------------------

```
auto merge of #11750 : bnoordhuis/rust/follow-rustc-symlink, r=thestinger

Before this commit, rustc looked in `dirname $0`/../lib for libraries
but that doesn't work when rustc is invoked through a symlink.

This commit makes rustc look in `dirname $(readlink $0)`/../lib, i.e.
it first canonicalizes the symlink before walking up the directory tree.

Fixes #3632.