Kill constants.h and fix some copyright headers.

Change-Id: I51c04d731d6de035328781d8ac134ad6fcf49897
diff --git a/src/oat/utils/assembler.h b/src/oat/utils/assembler.h
index 6fd150d..47f1ead 100644
--- a/src/oat/utils/assembler.h
+++ b/src/oat/utils/assembler.h
@@ -19,7 +19,9 @@
 
 #include <vector>
 
-#include "constants.h"
+#include "constants_arm.h"
+#include "constants_x86.h"
+#include "instruction_set.h"
 #include "logging.h"
 #include "macros.h"
 #include "managed_register.h"