etc: Suppress another Valgrind issue. rs=burningtree
libsyntax: add &self to parser methods
libsyntax: add &self to extensions
libsyntax: deny deprecated_self in libsyntax
auto merge of #5207 : erickt/rust/libsyntax-deprecated-self, r=brson

This adds an explicit `&self` to each method in libsyntax, and sets the `#[deny(deprecated_self)]` in `syntax.rc`.
rt: MIPS32 support
rustc: MIPS32 support
rustc: implement MIPS O32 ABI
rt: fix some bugs for MIPS target
There is no function in LLVM called LLVMInitializeMipsAsmLexer
Change the default level of unused_imports to warn
Remove unused imports throughout src/
Add a special FIXME for subduing warnings in rpath.rs
Adding missing imports for tests, and gate off others