librustc: Fix snake case errors.

librustc: Fix snake case errors.

A number of functions/methods have been moved or renamed to align
better with rust standard conventions.

rustc::back::link::WriteOutputFile => write_output_file
rustc::middle::ty::EmptyBuiltinBounds => empty_builtin_bounds
rustc::middle::ty::AllBuiltinBounds => all_builtin_bounds
rustc::middle::liveness::IrMaps => IrMaps::new
rustc::middle::liveness::Liveness => Liveness::new
rustc::middle::resolve::NameBindings => NameBindings::new
rustc::middle::resolve::PrimitiveTypeTable => PrimitiveTypeTable::new
rustc::middle::resolve::Resolver => Resolver::new
rustc::middle::trans::datum::Datum => Datum::new
rustc::middle::trans::datum::DatumBlock => DatumBlock::new
rustc::middle::trans::datum::Rvalue => Rvalue::new
rustc::middle::typeck::infer::new_ValsAndBindings => ::infer::unify::ValsAndBindings::new
rustc::middle::typeck::infer::region_inference::RegionVarBindings => RegionVarBindings::new

[breaking-change]