merge from android tree:
- optional parameters added to descriptorProc and allocPixels
- clip options to image decoders
- check for xfermode in blitter_a8
- UNROLL loops in blitrow

reviewed by reed@google.com



git-svn-id: http://skia.googlecode.com/svn/trunk@841 2bbb7eff-a529-9590-31e7-b0007b416f81
26 files changed