Fix up flags to SkGpuBlurUtils::GaussianBlur

src/core/SkMaskFilter.cpp

Index: src/core/SkMaskFilter.cpp
diff --git a/src/core/SkMaskFilter.cpp b/src/core/SkMaskFilter.cpp
index 86fc40ebacc3edaec3ee9a45cd55a0c74f60a339..fccce45a7705ece4e6b39c749df211c75c1ec94f 100644
--- a/src/core/SkMaskFilter.cpp
+++ b/src/core/SkMaskFilter.cpp
@@ -337,8 +337,7 @@ bool SkMaskFilter::directFilterRRectMaskGPU(GrTextureProvider* texProvider,
 bool SkMaskFilter::filterMaskGPU(GrTexture* src,
                                  const SkMatrix& ctm,
                                  const SkIRect& maskRect,
-                                 GrTexture** result,
-                                 bool canOverwriteSrc) const {
+                                 GrTexture** result) const {
     return false;
 }
 #endif