Support building GrGLInterface factory functions for both EGL and GLX.

Bug: skia:11293
Change-Id: Ie99c587fd8d466cb4260d8a78b9cff84a63315e2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/372200
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
10 files changed