New SkMutex benchmark - used when we suspected mutex performance issues;
committed not because they're a bottleneck now but because we might do
something with them in the future & it's quite lightweight.



git-svn-id: http://skia.googlecode.com/svn/trunk@2675 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed