Fix various issues with framebuffer fetch

src/gpu/glsl/GrGLSLCaps.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef GrGLSLCaps_DEFINED
 #define GrGLSLCaps_DEFINED
@@ skipping 73 matching lines @@
 
     bool usesPrecisionModifiers() const { return fUsesPrecisionModifiers; }
 
     // Returns whether we can use the glsl funciton any() in our shader code.
     bool canUseAnyFunctionInShader() const { return fCanUseAnyFunctionInShader; }
 
     bool canUseMinAndAbsTogether() const { return fCanUseMinAndAbsTogether; }
 
     bool mustForceNegatedAtanParamToFloat() const { return fMustForceNegatedAtanParamToFloat; }
 
+    bool requiresLocalOutputColorForFBFetch() const { return fRequiresLocalOutputColorForFBFetch; }
+
     // Returns the string of an extension that must be enabled in the shader to support
     // derivatives. If nullptr is returned then no extension needs to be enabled. Before calling
     // this function, the caller should check that shaderDerivativeSupport exists.
     const char* shaderDerivativeExtensionString() const {
         SkASSERT(this->shaderDerivativeSupport());
         return fShaderDerivativeExtensionString;
     }
 
     // Returns the string of an extension that will do all necessary coord transfomations needed
     // when reading the fragment position. If such an extension does not exisits, this function
@@ skipping 88 matching lines @@
     bool fNoPerspectiveInterpolationSupport : 1;
     bool fMultisampleInterpolationSupport : 1;
     bool fSampleVariablesSupport : 1;
     bool fSampleMaskOverrideCoverageSupport : 1;
     bool fExternalTextureSupport : 1;
     bool fTexelFetchSupport : 1;
 
     // Used for specific driver bug work arounds
     bool fCanUseMinAndAbsTogether : 1;
     bool fMustForceNegatedAtanParamToFloat : 1;
+    bool fRequiresLocalOutputColorForFBFetch : 1;
 
     const char* fVersionDeclString;
 
     const char* fShaderDerivativeExtensionString;
     const char* fFragCoordConventionsExtensionString;
     const char* fSecondaryOutputExtensionString;
     const char* fExternalTextureExtensionString;
     const char* fTexelBufferExtensionString;
     const char* fNoPerspectiveInterpolationExtensionString;
     const char* fMultisampleInterpolationExtensionString;
@@ skipping 14 matching lines @@
 
     uint8_t fSamplerPrecisions[(1 << kGrShaderTypeCount)][kGrPixelConfigCnt];
 
     friend class GrGLCaps;  // For initialization.
     friend class GrVkCaps;
 
     typedef GrShaderCaps INHERITED;
 };
 
 #endif