Move hot utf routines into -inl.h.

Change-Id: I7050d8282a7e5870b2bf671d6867c57625e00ccc
diff --git a/runtime/dex_file.cc b/runtime/dex_file.cc
index e81c456..098ab67 100644
--- a/runtime/dex_file.cc
+++ b/runtime/dex_file.cc
@@ -38,7 +38,7 @@
 #include "safe_map.h"
 #include "thread.h"
 #include "UniquePtr.h"
-#include "utf.h"
+#include "utf-inl.h"
 #include "utils.h"
 #include "well_known_classes.h"
 #include "zip_archive.h"