Documentation examples for LruCache.
Cleanup LruCache doc.
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.
rustdoc: Add a --target flag

Closes #13893
rustdoc: Hide impls for #[doc(hidden)] traits

Closes #14585
rustdoc: Bind keydown instead of keypress for nav

Apparently keypress doesn't quite work in all browsers due to some not invoking
the handler and jquery not setting the right `which` field in all circumstances.
According to http://stackoverflow.com/questions/2166771 switching over to
`keydown` works and it appears to do the trick. Tested in Safari, Firefox, and
Chrome.

Closes #15011
rustdoc: Fix inlining type parameters

I'm not entirely sure if the correct space can be inferred when cleaning
Generics, so the impl has been switched to take the space explicitly.

Closes #15099
rustdoc: Fix links to Box/Gc

These are lang items now, so the internal representations need to be
re-translated back to the original structures manually.

Closes #15185
Closes #15800
rustdoc: Correctly handle local renamings

Previously a `pub use` would not rename the destination in rustdoc, it would
always use the destination ident instead of the renamed ident.
rustdoc: Inline items from foreign mods

These were all just previously skipped.

Closes #15648
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.
Implement PartialEq/Eq/Clone/Hash/FromIterator/Extendable for SmallIntMap and Show/Clone for TrieMap and TrieSet