row_msa fix clang build warnings.
row_msa fix clang build warnings.

BUG=libyuv:634
TEST=untested

Change-Id: Ib7f0c99e669ddba0a1efbd15895880281ad6303e
Reviewed-on: https://chromium-review.googlesource.com/435303
Reviewed-by: Frank Barchard <52415189a3f67d375195cbbb6fdb1f1759498e57@google.com>

lemenkov/libyuv,lemenkov/libyuv,lemenkov/libyuv,lemenkov/libyuv