Release VectorDrawable cache surface on render thread

Release VectorDrawable cache surface on render thread.
This is fixing an assert in skia GrSingleOwner.h:33.

Test: Ran gmail before and after the change.
Bug: 64842607
Change-Id: I46e0c2557ac5b2fc3be2cc2d35abf96f6d6c9399
diff --git a/libs/hwui/renderthread/RenderThread.cpp b/libs/hwui/renderthread/RenderThread.cpp
index 72a428f..51e9374 100644
--- a/libs/hwui/renderthread/RenderThread.cpp
+++ b/libs/hwui/renderthread/RenderThread.cpp
@@ -499,6 +499,10 @@
     return nullptr;
 }
 
+bool RenderThread::isCurrent() {
+    return gettid() == getInstance().getTid();
+}
+
 } /* namespace renderthread */
 } /* namespace uirenderer */
 } /* namespace android */