Improve time to texture destruction

Eliminate textureCache.mGarbage which is only cleared
in a trimMemory. Instead when we hit ~Bitmap post a
message to RenderThread to release the texture immediately

Bug: 38258699
Test: manual
Change-Id: I962ba275e89afb628ba02f74769287edbab9fed4
diff --git a/libs/hwui/renderstate/RenderState.cpp b/libs/hwui/renderstate/RenderState.cpp
index c8833d2..b89272e 100644
--- a/libs/hwui/renderstate/RenderState.cpp
+++ b/libs/hwui/renderstate/RenderState.cpp
@@ -122,6 +122,13 @@
     mCaches->flush(mode);
 }
 
+void RenderState::onBitmapDestroyed(uint32_t pixelRefId) {
+    if (mCaches->textureCache.destroyTexture(pixelRefId)) {
+        glFlush();
+        GL_CHECKPOINT(MODERATE);
+    }
+}
+
 void RenderState::setViewport(GLsizei width, GLsizei height) {
     mViewportWidth = width;
     mViewportHeight = height;