Add setXi and setXiv in GrGLSLProgramDataManager.

Previously, X = 1; this CL adds X = [2, 3, 4] to match the equivalent
vector support for floats.

It currently does not define any methods for setting unsigned integers
or for setting explicitly lower bit count integers.

Bug: skia:
Change-Id: Iaa1e9a6b979208a8c30b07b8ccb0792b3dd64c97
Reviewed-on: https://skia-review.googlesource.com/150261
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
7 files changed