Create new target to hold gpu test code, enable direct testing of GrEffects in GM.

gm/bleed.cpp

Index: gm/bleed.cpp
diff --git a/gm/bleed.cpp b/gm/bleed.cpp
index b61284122b969347133e4bf8ccc17eb893248f02..2d3743a5a25e976439795817fd3eb38cb27fe213 100644
--- a/gm/bleed.cpp
+++ b/gm/bleed.cpp
@@ -15,10 +15,6 @@
 namespace skiagm {
 extern GrContext* GetGr();
 };
-
-void GrContext::setMaxTextureSizeOverride(int maxTextureSizeOverride) {
-    fMaxTextureSizeOverride = maxTextureSizeOverride;
-}
 #endif
 
 // Create a black&white checked texture with a 1-pixel red ring