We've reconsidered previous patch in IRC.

It's more useful to completely ignore alpha for display of straight
colors.

Supporting straight pipeline is possible, but not a topic for bcon4.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54430 954f8c5b-7b00-dc11-b283-0030488c597c