fix up GrGLProgrambuilder precision on varyings

src/gpu/gl/builders/GrGLVertexShaderBuilder.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLVertexShader_DEFINED
 #define GrGLVertexShader_DEFINED
 
@@ skipping 14 matching lines @@
                                        GrVertexAttribTypeToSLType(attr->fType),
                                        GrShaderVar::kAttribute_TypeModifier,
                                        GrShaderVar::kNonArray,
                                        attr->fPrecision));
     }
 
 private:
     /*
      * Internal call for GrGLProgramBuilder.addVarying
      */
-    void addVarying(const char* name, GrGLVarying*);
+    void addVarying(const char* name, GrSLPrecision, GrGLVarying*);
 
     /*
      * private helpers for compilation by GrGLProgramBuilder
      */
     void bindVertexAttributes(GrGLuint programID);
     bool compileAndAttachShaders(GrGLuint programId, SkTDArray<GrGLuint>* shaderIds);
 
     // an internal call which checks for uniquness of a var before adding it to the list of inputs
     bool addAttribute(const GrShaderVar& var);
 
     const char* fRtAdjustName;
 
     friend class GrGLProgramBuilder;
 
     typedef GrGLShaderBuilder INHERITED;
 };
 
 #endif