Make imagealphathreshold GM skip replay modes until it is fixed.

gm/imagealphathreshold.cpp

Index: gm/imagealphathreshold.cpp
diff --git a/gm/imagealphathreshold.cpp b/gm/imagealphathreshold.cpp
index 7597090aa872bfa9a0510c6e57687d15e47a427b..1600be98979340b7c6e56edc8aeb19f2bdd38916 100644
--- a/gm/imagealphathreshold.cpp
+++ b/gm/imagealphathreshold.cpp
@@ -22,7 +22,11 @@ public:
 
 protected:
     virtual uint32_t onGetFlags() const SK_OVERRIDE {
-        return this->INHERITED::onGetFlags() | GM::kSkipTiled_Flag;
+        return this->INHERITED::onGetFlags() |
+               GM::kSkipTiled_Flag |
+               GM::kSkipPicture_Flag |
+               GM::kSkipPipe_Flag | 
+               GM::kSkipPipeCrossProcess_Flag;
     }
 
     virtual SkString onShortName() SK_OVERRIDE {