Move rs.h includes to source files.

Change-Id: Ic49e3fa5580c67f35a21f95872794ea03dd114b6
diff --git a/cpp/Allocation.cpp b/cpp/Allocation.cpp
index 9f3ce20..d2d81c9 100644
--- a/cpp/Allocation.cpp
+++ b/cpp/Allocation.cpp
@@ -15,6 +15,7 @@
  */
 
 #include "RenderScript.h"
+#include <rs.h>
 
 using namespace android;
 using namespace RSC;