Adding base type changes related to Uniform Blocks

This cl should be a NOOP. It simply adds some basic
functionality in BaseTypes.h that will be useful in
eventually enabling Uniform Blocks in the parser.

Change-Id: I0c2b3200e0ae95ddce86367663081c2aef751308
Reviewed-on: https://swiftshader-review.googlesource.com/3311
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>