Rename glrt::fRTFBOID -> fMultisampleFBOID

As part of this we also create two fbos now for
multisampled_render_to_texture: one msaa and one not.

Bug: skia:11396
Change-Id: If519b52ec79de4b2abeac2c5658f766f1c7e8d9c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/392746
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
6 files changed