Rename vars and functions from 'glslcaps'->'shadercaps'

Change-Id: I34d226d866dd4ba8e5f33f95cb8cbf01292f9314
Reviewed-on: https://skia-review.googlesource.com/5312
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
45 files changed