Conditionally cache RenderEffect results

Added property to conditionally cache SkImage instances
with SkImageFilters applied. Some GL vendor implementations
invoke Fence::waitForver without signalling, leading
to ANRs throughout the system.

Bug: 193145089
Test: manual
Change-Id: I3e478b11b66205d96e9499a362f7412a1d6e952d
diff --git a/libs/hwui/Properties.h b/libs/hwui/Properties.h
index 7df6e2c..d224a54 100644
--- a/libs/hwui/Properties.h
+++ b/libs/hwui/Properties.h
@@ -224,6 +224,7 @@
     static bool skipEmptyFrames;
     static bool useBufferAge;
     static bool enablePartialUpdates;
+    static bool enableRenderEffectCache;
 
     // TODO: Move somewhere else?
     static constexpr float textGamma = 1.45f;