Replace fWillReadFragmentPosition with a bitfield

src/gpu/glsl/GrGLSLFragmentShaderBuilder.h

Index: src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
diff --git a/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h b/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
index b9816af71a2a014ea8eb1388443078993c8fa4a5..05185eb0359c7b81defee4d3b38d3807c2499aae 100644
--- a/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
+++ b/src/gpu/glsl/GrGLSLFragmentShaderBuilder.h
@@ -10,6 +10,7 @@
 
 #include "GrGLSLShaderBuilder.h"
 
+#include "GrProcessor.h"
 #include "glsl/GrGLSLProcessorTypes.h"
 
 class GrRenderTarget;
@@ -171,14 +172,16 @@ private:
     const char* getPrimaryColorOutputName() const;
     const char* getSecondaryColorOutputName() const;
 
+#ifdef SK_DEBUG
     // As GLSLProcessors emit code, there are some conditions we need to verify.  We use the below
     // state to track this.  The reset call is called per processor emitted.
+    bool usedBuiltInState() const { return fUsedBuiltInState; }
     bool hasReadDstColor() const { return fHasReadDstColor; }
-    bool hasReadFragmentPosition() const { return fHasReadFragmentPosition; }
-    void reset() {
+    void resetVerification() {
+        fUsedBuiltInState = GrProcessor::kNone_BuiltInState;
         fHasReadDstColor = false;
-        fHasReadFragmentPosition = false;
     }
+#endif
 
     static const char* DeclaredColorOutputName() { return "fsColorOut"; }
     static const char* DeclaredSecondaryColorOutputName() { return "fsSecondaryColorOut"; }
@@ -226,10 +229,12 @@ private:
     bool fHasSecondaryOutput;
     bool fHasInitializedSampleMask;
 
+#ifdef SK_DEBUG
     // some state to verify shaders and effects are consistent, this is reset between effects by
     // the program creator
+    GrProcessor::BuiltInState fUsedBuiltInState;
     bool fHasReadDstColor;
-    bool fHasReadFragmentPosition;
+#endif
 
     friend class GrGLSLProgramBuilder;
     friend class GrGLProgramBuilder;