Removed a few unnecessary/bad instructions from PixelProgram and
VertexProgram. Also added the proper implementation for printing out
a shader instruction that includes indexing an array with a uniform.

Change-Id: Icd37dd4f70419874bb65c54438409b8b9c3ee836
Reviewed-on: https://swiftshader-review.googlesource.com/4753Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>