More header untangling.

Change-Id: I090943775cbda8d9515cdb484957f6b05d5b1799
diff --git a/rsProgramVertex.cpp b/rsProgramVertex.cpp
index c8a53ea..23fcbe7 100644
--- a/rsProgramVertex.cpp
+++ b/rsProgramVertex.cpp
@@ -16,6 +16,7 @@
 
 #include "rsContext.h"
 #include "rsProgramVertex.h"
+#include "rsMatrix4x4.h"
 
 using namespace android;
 using namespace android::renderscript;