rustpkg: Implement --version command-line option

Now, rustpkg --version does something useful!
Don't make the runtime exit on illegal calls
Decrement unkillable counter before failing
auto merge of #8712 : catamorphism/rust/rustpkg-issue-7241, r=pcwalton

r? @brson ...multiple workspaces

The test checks that rustpkg uses the first one, rather than complaining
about multiple matches.

Closes #7241
Add a Default trait.
Fix deriving-zero test
auto merge of #8438 : cmr/rust/default, r=thestinger
Fix valgrind suppression on mac

This callstack changed when the FFI did. I am still a little frightened by
this suppression.
std: Make vec::from_elem failure-safe
auto merge of #8739 : fhahn/rust/ticket_2275, r=brson

This is a pull request for #2275

I've created a small python script to generate test files for a list of keywords (as break do else enum extern false fn for if impl let loop match mod mut priv pub ref return self static struct super true trait type unsafe use while), but I'm not really sure where to put it. I've added the created files as well.

I did not use 

     fn main() {
        let $KW = "foo"; //~ error
        println($KW); //~ error
    } 

as template, because for return, self, ref, loop, mut and break this does not raise an error in the ```println``` line, only in the ```let``` line.
Rewrote module tutorial
auto merge of #8747 : pnkfelix/rust/fsk-issue6887-fix-emacs-compilation-regexp, r=graydon

Fix #6887
Rewrite pass management with LLVM

Beforehand, it was unclear whether rust was performing the "recommended set" of
optimizations provided by LLVM for code. This commit changes the way we run
passes to closely mirror that of clang, which in theory does it correctly. The
notable changes include:

* Passes are no longer explicitly added one by one. This would be difficult to
  keep up with as LLVM changes and we don't guaranteed always know the best
  order in which to run passes
* Passes are now managed by LLVM's PassManagerBuilder object. This is then used
  to populate the various pass managers run.
* We now run both a FunctionPassManager and a module-wide PassManager. This is
  what clang does, and I presume that we *may* see a speed boost from the
  module-wide passes just having to do less work. I have no measured this.
* The codegen pass manager has been extracted to its own separate pass manager
  to not get mixed up with the other passes
* All pass managers now include passes for target-specific data layout and
  analysis passes

Some new features include:

* You can now print all passes being run with `-Z print-llvm-passes`
* When specifying passes via `--passes`, the passes are now appended to the
  default list of passes instead of overwriting them.
* The output of `--passes list` is now generated by LLVM instead of maintaining
  a list of passes ourselves
* Loop vectorization is turned on by default as an optimization pass and can be
  disabled with `-Z no-vectorize-loops`
auto merge of #8700 : alexcrichton/rust/better-llvm, r=thestinger

Beforehand, it was unclear whether rust was performing the "recommended set" of
optimizations provided by LLVM for code. This commit changes the way we run
passes to closely mirror that of clang, which in theory does it correctly. The
notable changes include:

* Passes are no longer explicitly added one by one. This would be difficult to
  keep up with as LLVM changes and we don't guaranteed always know the best
  order in which to run passes
* Passes are now managed by LLVM's PassManagerBuilder object. This is then used
  to populate the various pass managers run.
* We now run both a FunctionPassManager and a module-wide PassManager. This is
  what clang does, and I presume that we *may* see a speed boost from the
  module-wide passes just having to do less work. I have no measured this.
* The codegen pass manager has been extracted to its own separate pass manager
  to not get mixed up with the other passes
* All pass managers now include passes for target-specific data layout and
  analysis passes

Some new features include:

* You can now print all passes being run with `-Z print-llvm-passes`
* When specifying passes via `--passes`, the passes are now appended to the
  default list of passes instead of overwriting them.
* The output of `--passes list` is now generated by LLVM instead of maintaining
  a list of passes ourselves
* Loop vectorization is turned on by default as an optimization pass and can be
  disabled with `-Z no-vectorize-loops`


All of these "copies" of clang are based off their [source code](http://clang.llvm.org/doxygen/BackendUtil_8cpp_source.html) in case anyone is curious what my source is. I was hoping that this would fix #8665, but this does not help the performance issues found there. Hopefully i'll allow us to tweak passes or see what's going on to try to debug that problem.
auto merge of #8757 : vadimcn/rust/debug-info-tests, r=brson

Now that new LLVM has landed, the debug info works on Windows as well.   Most existing tests pass, except for the following four, which I left disabled for now:
lexical-scope-in-for-loop
lexical-scope-in-if
lexical-scope-in-match
lexical-scopes-in-block-expression

Also, fixed a small problem with the debug info test runner.
Rebased and replaced yield with deschedule
auto merge of #8773 : catamorphism/rust/rustpkg-version-flag, r=anasazi

r? anyone. Now, rustpkg --version does something useful!
Rename UnsafeAtomicRcBox to UnsafeArc. Fixes #7674.
fix typo in rust-mode.el
auto merge of #8779 : brson/rust/macsupp, r=thestinger

This callstack changed when the FFI did. I am still a little frightened by
this suppression.

cc #8253