Fix invalid use of intThresholdCompare in fragment_ops tests

Blend and random tests in fragment_ops tests were comparing RGB to RGBA
image using intThresholdCompare, which doesn't work as expected after
recent getPixelInt() fix for RGB8.

Bug: 25111313
Change-Id: Iac27bfcad7fb2ca11d9f4af44418cd1cbd72a2f5
4 files changed