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.h b/libs/hwui/renderthread/RenderThread.h
index bef47b3..30884b5 100644
--- a/libs/hwui/renderthread/RenderThread.h
+++ b/libs/hwui/renderthread/RenderThread.h
@@ -111,6 +111,14 @@
     sk_sp<Bitmap> allocateHardwareBitmap(SkBitmap& skBitmap);
     void dumpGraphicsMemory(int fd);
 
+    /**
+     * isCurrent provides a way to query, if the caller is running on
+     * the render thread.
+     *
+     * @return true only if isCurrent is invoked from the render thread.
+     */
+    static bool isCurrent();
+
 protected:
     virtual bool threadLoop() override;