Add GLSL support for texelFetch

src/gpu/gl/GrGLInterface.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "gl/GrGLInterface.h"
 #include "gl/GrGLExtensions.h"
@@ skipping 396 matching lines @@
             RETURN_FALSE_INTERFACE
         }
     }
 
     if (kGL_GrGLStandard == fStandard) {
         if (glVer >= GR_GL_VER(3,1)) {
             if (nullptr == fFunctions.fTexBuffer) {
                 RETURN_FALSE_INTERFACE;
             }
         }
+        if (glVer >= GR_GL_VER(4,3)) {
+            if (nullptr == fFunctions.fTexBufferRange) {
+                RETURN_FALSE_INTERFACE;
+            }
+        }
     } else {
         if (glVer >= GR_GL_VER(3,2) || fExtensions.has("GL_OES_texture_buffer") ||
             fExtensions.has("GL_EXT_texture_buffer")) {
-            if (nullptr == fFunctions.fTexBuffer) {
+            if (nullptr == fFunctions.fTexBuffer ||
+                nullptr == fFunctions.fTexBufferRange) {
                 RETURN_FALSE_INTERFACE;
             }
         }
     }
 
     if (kGL_GrGLStandard == fStandard) {
         if (glVer >= GR_GL_VER(3, 0) || fExtensions.has("GL_ARB_vertex_array_object")) {
             if (nullptr == fFunctions.fBindVertexArray ||
                 nullptr == fFunctions.fDeleteVertexArrays ||
                 nullptr == fFunctions.fGenVertexArrays) {
@@ skipping 348 matching lines @@
 
     if (fExtensions.has("EGL_KHR_image") || fExtensions.has("EGL_KHR_image_base")) {
         if (nullptr == fFunctions.fEGLCreateImage ||
             nullptr == fFunctions.fEGLDestroyImage) {
             RETURN_FALSE_INTERFACE
         }
     }
 
     return true;
 }