Create GrGLSLVaryingHandler class for program building

src/gpu/glsl/GrGLSLShaderBuilder.h

Index: src/gpu/glsl/GrGLSLShaderBuilder.h
diff --git a/src/gpu/glsl/GrGLSLShaderBuilder.h b/src/gpu/glsl/GrGLSLShaderBuilder.h
index fde48dc57004b941c9049d85dc7d2e8937011df0..1a8255dbb46e73d8804542eda39d78cb97e36ea6 100644
--- a/src/gpu/glsl/GrGLSLShaderBuilder.h
+++ b/src/gpu/glsl/GrGLSLShaderBuilder.h
@@ -25,9 +25,6 @@ public:
     GrGLSLShaderBuilder(GrGLSLProgramBuilder* program);
     virtual ~GrGLSLShaderBuilder() {}
 
-    void addInput(const GrGLSLShaderVar& input) { fInputs.push_back(input); }
-    void addOutput(const GrGLSLShaderVar& output) { fOutputs.push_back(output); }
-
     /*
      * We put texture lookups in the base class because it is TECHNICALLY possible to do texture
      * lookups in any kind of shader.  However, for the time being using these calls on non-fragment