NEON version of YUV422TORGB is updated based on C algorithm. Accuracy YUV to RGB
of NEON is also updated according to test result. Macro LIBYUV_NEON is added to
identify accuracy YUV to RGB for ARM platform.
Except TestJ420 and TestYUV, all the other tests are passed.

BUG=324
TESTED=libyuvTest on ARMv7 with Android
R=fbarchard@google.com

Change-Id: I492ca628679940534f40341721dc5b6dc2d7a5b6

Review URL: https://webrtc-codereview.appspot.com/40609004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@1296 16f28f9a-4ce2-e073-06de-1de4eb20be90