Quick and dirty port to latest rustc

This change ports the code from rust commit
1bfa45cfd9d7c8b2dcc0ea7a42396624e8b5a31b (2013-11-12) to commit
25431774a933a3b0c5212ea45150660544dec1ec (today).

This commit disables the benchmark for SpinWaitStrategy until I find
time to rewrite the benchmark to use 1:1 task scheduling for it again.
The YieldWaitStrategy benchmark produces results that are almost as high
as SpinWaitStrategy's, so this is acceptable in the short term.
Fix unnecessary_parens warnings
Remove dead code
Disable dead-code warning

It seems to warn spuriously about inlined functions, which makes the
signal-to-noise ratio very low.
Enable LTO on the main benchmark build

This produces a small but noticeable speedup.