Lock gFTMutex when modifying FT globals.

This prevents a crash when running bench_pictures with multiple threads.

Also remove an unused function and fix a typo in SkFontHost.
Review URL: https://codereview.appspot.com/6625043

git-svn-id: http://skia.googlecode.com/svn/trunk@5816 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed