I420ToARGB1555, I420ToARGB4444, I420ToRGB565, ARGBToARGB1555, ARGBToARGB4444, and ARGBToRGB565 done with shared macro for conversion in 1 step NEON.
BUG=139
TEST=libyuv_unittest --gtest_filter=*I420To*RGB???*_*
Review URL: https://webrtc-codereview.appspot.com/928013

git-svn-id: http://libyuv.googlecode.com/svn/trunk@460 16f28f9a-4ce2-e073-06de-1de4eb20be90