Apparently better not to use values like 1.0f in GLSL code

Fix from debug session of self and Ton, was affecting OSX
builds, making GLSL display transform not working on this
platform.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56342 954f8c5b-7b00-dc11-b283-0030488c597c