print on unused uniforms in debug builds

src/gpu/gl/GrGLProgramDataManager.h

Index: src/gpu/gl/GrGLProgramDataManager.h
diff --git a/src/gpu/gl/GrGLProgramDataManager.h b/src/gpu/gl/GrGLProgramDataManager.h
index f893d181ec2502c1cb3c131529aa657641b8939d..5ee1a85557e14a9bbc12a903f6ca64c04d67579e 100644
--- a/src/gpu/gl/GrGLProgramDataManager.h
+++ b/src/gpu/gl/GrGLProgramDataManager.h
@@ -106,6 +106,12 @@ private:
         );
     };
 
+#ifdef SK_DEBUG
+    void printUnused(const Uniform&) const;
+#else
+    void printUnused(const Uniform&) const {}
+#endif
+
     SkTArray<Uniform, true> fUniforms;
     GrGLGpu* fGpu;