Add "const". And clean up.

Change-Id: I70e6994a0cd1d897e6981d5642108fee1324708f
diff --git a/lib/ExecutionEngine/Script.h b/lib/ExecutionEngine/Script.h
index ef682a6..fbe4956 100644
--- a/lib/ExecutionEngine/Script.h
+++ b/lib/ExecutionEngine/Script.h
@@ -221,7 +221,7 @@
 #if USE_CACHE
     int internalLoadCache(bool checkOnly);
 #endif
-    int internalCompile(CompilerOption&);
+    int internalCompile(const CompilerOption&);
 
   };