Start to propagate constness of GrPipelineBuilder up the stack

gm/constcolorprocessor.cpp

Index: gm/constcolorprocessor.cpp
diff --git a/gm/constcolorprocessor.cpp b/gm/constcolorprocessor.cpp
index 661a5ea8a4b142c97d02f03da8cdff03f61715e7..e763305f3b4a94c10885fd7de742fa7757943d5e 100644
--- a/gm/constcolorprocessor.cpp
+++ b/gm/constcolorprocessor.cpp
@@ -115,7 +115,7 @@ protected:
                     GrPipelineBuilder pipelineBuilder(grPaint, rt, clip);
                     pipelineBuilder.addColorProcessor(fp);
 
-                    tt.target()->drawSimpleRect(&pipelineBuilder,
+                    tt.target()->drawSimpleRect(pipelineBuilder,
                                                 grPaint.getColor(),
                                                 viewMatrix,
                                                 renderRect);