mk: Add check-secondary target for tests with no x-platform risk.

We'll use this to run a subset of the test suite onto a dedicated
bot.

This puts the grammar tests and the pretty-printer tests under
check-secondary. It leanves the pretty tests under plain `check`
for now, until the new bot is added to take over.

Because check-secondary is not run as part of `make check` there
will be a set of tests that most users never run and are only
checked by bors. I think this will be ok because grammar tests
should rarely regress, and the people regressing such tests
should have the fortitude to deal with it.
mk: Add comments to primary check targets
mk: Some fixes to grammar.mk

Invoke rustc in a way that sets LD_LIBRARY_PATH,
and disable the deps on RustLexer.class when antlr isn't available.
rustc: Future proof runtime injection

Rename and gensym the runtime on import, so that users
can't refer to the `native` crate.

This is unlikely to break code, but users should import the "native" crate directly.

[breaking-change]
mk: Remove check-syntax target

This appears to be redundantly named with a shortcut target for
testing the syntax crate.
mk: Print grammar info message like others
librustc: Resolve regions and report errors in trait/impl method
matching.

This breaks code like:

    struct Foo<'a,'b> {
        x: &'a int,
        y: &'b int,
    }

    trait Tr {
        fn foo(x: Self) {}
    }

    impl<'a,'b> Tr for Foo<'a,'b> {
        fn foo(x: Foo<'b,'a>) {} // <-- bad
    }

Change this code to not contain a lifetime mismatch error. For example:

    struct Foo<'a,'b> {
        x: &'a int,
        y: &'b int,
    }

    trait Tr {
        fn foo(x: Self) {}
    }

    impl<'a,'b> Tr for Foo<'a,'b> {
        fn foo(x: Foo<'a,'b>) {} // OK
    }

Closes #15517.

[breaking-change]
librustc: Use builder for llvm attributes.
Add tests that the injected runtime is inaccessible
librustc: Use dereferenceable attribute instead of nonnull where we can.
Fix a typo in SmallIntMap documentation
rustllvm: Stub out some functions for llvm < 3.5
fix small typo in guide-lifetimes
auto merge of #15987 : brson/rust/hidestdrt, r=alexcrichton

Rename and gensym the runtime on import, so that users
can't refer to the `native` crate.

This is unlikely to break code, but users should import the "native" crate directly.

[breaking-change]

cc @alexcrichton
auto merge of #15988 : brson/rust/antlrprep, r=cmr

Add `check-secondary`, which runs the pretty and lexer tests so we can run them on a dedicated bot. Leaves the pretty tests running under `check` until the bots are switched over. Also fixes some issues.

r? @cmr
auto merge of #15991 : pcwalton/rust/resolve-regions-in-trait-matching, r=alexcrichton

matching.

This breaks code like:

    struct Foo<'a,'b> {
        x: &'a int,
        y: &'b int,
    }

    trait Tr {
        fn foo(x: Self) {}
    }

    impl<'a,'b> Tr for Foo<'a,'b> {
        fn foo(x: Foo<'b,'a>) {} // <-- bad
    }

Change this code to not contain a lifetime mismatch error. For example:

    struct Foo<'a,'b> {
        x: &'a int,
        y: &'b int,
    }

    trait Tr {
        fn foo(x: Self) {}
    }

    impl<'a,'b> Tr for Foo<'a,'b> {
        fn foo(x: Foo<'a,'b>) {} // OK
    }

Closes #15517.

[breaking-change]

r? @alexcrichton
auto merge of #15996 : nham/rust/smallintmap_not_hashmap, r=sanxiyn

SmallIntMap doesn't involve hashing?
auto merge of #15998 : luqmana/rust/nmnnbd, r=thestinger

LLVM recently added a new attribute, dereferenceable: http://reviews.llvm.org/D4449

>This patch adds a dereferencable attribute. In some sense, this is a companion to the nonnull attribute, but specifies that the pointer is known to be dereferencable in the same sense as a pointer generated by alloca is known to be dereferencable.

With rust, everywhere that we previously marked `nonnull` we can actually mark as `dereferenceable` (which implies nonnull) since we know the size. That is, except for one case: when generating calls for TyVisitor. It seems like we haven't substituted the self type (so we have `ty_param`) and just treat it as an opaque pointer so I just left that bit as nonnull.

With this, LLVM can for example hoist a load out of a loop where it previously couldn't:

```Rust
pub fn baz(c: &uint, n: uint) -> uint {
    let mut res = 0;
    for i in range(0, n) {
        if i > 0 {
            res += *c * i;
        }
    }
    res
}
```

Before:
```llvm
define i64 @baz(i64* noalias nocapture nonnull readonly, i64) unnamed_addr #0 {
entry-block:
  br label %for_loopback.outer

for_loopback.outer:                               ; preds = %then-block-33-, %entry-block
  %.ph = phi i64 [ %.lcssa, %then-block-33- ], [ 0, %entry-block ]
  %res.0.ph = phi i64 [ %8, %then-block-33- ], [ 0, %entry-block ]
  br label %for_loopback

for_exit:                                         ; preds = %for_loopback
  %res.0.ph.lcssa = phi i64 [ %res.0.ph, %for_loopback ]
  ret i64 %res.0.ph.lcssa

for_loopback:                                     ; preds = %for_loopback.outer, %for_body
  %2 = phi i64 [ %4, %for_body ], [ %.ph, %for_loopback.outer ]
  %3 = icmp ult i64 %2, %1
  br i1 %3, label %for_body, label %for_exit

for_body:                                         ; preds = %for_loopback
  %4 = add i64 %2, 1
  %5 = icmp eq i64 %2, 0
  br i1 %5, label %for_loopback, label %then-block-33-

then-block-33-:                                   ; preds = %for_body
  %.lcssa = phi i64 [ %4, %for_body ]
  %.lcssa15 = phi i64 [ %2, %for_body ]
  %6 = load i64* %0, align 8                     ; <------- this load
  %7 = mul i64 %6, %.lcssa15
  %8 = add i64 %7, %res.0.ph
  br label %for_loopback.outer
}
```

After:
```llvm
define i64 @baz(i64* noalias nocapture readonly dereferenceable(8), i64) unnamed_addr #0 {
entry-block:
  %2 = load i64* %0, align 8                    ; <------- load once instead
  br label %for_loopback.outer

for_loopback.outer:                               ; preds = %then-block-33-, %entry-block
  %.ph = phi i64 [ %.lcssa, %then-block-33- ], [ 0, %entry-block ]
  %res.0.ph = phi i64 [ %8, %then-block-33- ], [ 0, %entry-block ]
  br label %for_loopback

for_exit:                                         ; preds = %for_loopback
  %res.0.ph.lcssa = phi i64 [ %res.0.ph, %for_loopback ]
  ret i64 %res.0.ph.lcssa

for_loopback:                                     ; preds = %for_loopback.outer, %for_body
  %3 = phi i64 [ %5, %for_body ], [ %.ph, %for_loopback.outer ]
  %4 = icmp ult i64 %3, %1
  br i1 %4, label %for_body, label %for_exit

for_body:                                         ; preds = %for_loopback
  %5 = add i64 %3, 1
  %6 = icmp eq i64 %3, 0
  br i1 %6, label %for_loopback, label %then-block-33-

then-block-33-:                                   ; preds = %for_body
  %.lcssa = phi i64 [ %5, %for_body ]
  %.lcssa15 = phi i64 [ %3, %for_body ]
  %7 = mul i64 %2, %.lcssa15
  %8 = add i64 %7, %res.0.ph
  br label %for_loopback.outer
}
```
auto merge of #16000 : emkay/rust/lifetimes-guide-typo, r=alexcrichton
Add examples for RingBuf methods get, get_mut, iter, mut_iter