Add ASTC LDR error colour quality warning

Add ASTC LDR error colour quality warning

Some hardware can output the HDR error colour (black) instead of the
LDR error colour (magenta). Valid compression blocks are rendered
correctly.

This change adds a second comparison mechanism if the initial *fast*
deMemCmp fails; the texture values are compared allowing for any value
matching an error colour to compare against the other error colour.

If such a match is detected the test will output a QualityWarning
instead of a Pass.

If the two compared values don't match, but are not both error colours
the test result is still a Fail.

Affects:

dEQP-VK.image.texel_view_compatible*astc*

Components: Vulkan

VK-GL-CTS issue: 1231

Change-Id: Ie14913de0f2f3cf7fed90c275e48c67181c1e7ff