Clean up physical coupling

Narrow the use of #include directives in hwui, replacing with forward
declarations where straightforward. Speeds compiles; doesn't do any
restructuring of code.

Change-Id: Icac2baffb5896f55d8c6718e9bd9d4bfa02d3ca0
diff --git a/libs/hwui/AmbientShadow.cpp b/libs/hwui/AmbientShadow.cpp
index cb3a002..278ed29 100644
--- a/libs/hwui/AmbientShadow.cpp
+++ b/libs/hwui/AmbientShadow.cpp
@@ -60,6 +60,7 @@
 #include "AmbientShadow.h"
 #include "ShadowTessellator.h"
 #include "Vertex.h"
+#include "VertexBuffer.h"
 #include "utils/MathUtils.h"
 
 namespace android {