Add macro to decide GrGLStandard

This allows us to remove certain interfaces at compile time.

This replaces most (all?) of the cases where it was
if (gl) else [implicit gles] to be explicitly
if (gl) else if (gles)
in preparation for adding a WebGL standard.

For consistency, I tried to check first for GL, then for
GLES, which involved re-arranging a few if blocks.

PS 3 removes about 1.2KB (0.4 KB gzipped) from CanvasKit by
removing the GrGLInterface related checks from
GrGlInterface::validate()

PS 8 removes a total of 6.0 KB (2.6 KB gzipped) from
GrGlInterface::validate() and GrGlCaps::*

Bug: skia:8378
Change-Id: Ia91b732d888907f5d94b0eac8ca023084999fa7e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/201604
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
diff --git a/src/gpu/gl/GrGLContext.cpp b/src/gpu/gl/GrGLContext.cpp
index a2a5a3b..1c570e5 100644
--- a/src/gpu/gl/GrGLContext.cpp
+++ b/src/gpu/gl/GrGLContext.cpp
@@ -58,7 +58,7 @@
     // extension to be enabled, even when using ESSL3. Some devices appear to only support the ES2
     // extension. As an extreme (optional) solution, we can fallback to using ES2 shading language
     // if we want to prioritize external texture support. skbug.com/7713
-    if (kGLES_GrGLStandard == interface->fStandard &&
+    if (GR_IS_GR_GL_ES(interface->fStandard) &&
         options.fPreferExternalImagesOverES3 &&
         !options.fDisableDriverCorrectnessWorkarounds &&
         interface->hasExtension("GL_OES_EGL_image_external") &&