Fixes style nitpick

Change-Id: Ic3a7119ce7ca9bfae0dbf7af4d285f44d3a72a3e
diff --git a/compiler/output_stream.h b/compiler/output_stream.h
index b5ac933..97ccc2c 100644
--- a/compiler/output_stream.h
+++ b/compiler/output_stream.h
@@ -18,9 +18,10 @@
 #define ART_COMPILER_OUTPUT_STREAM_H_
 
 #include <stdint.h>
-#include <string>
 #include <sys/types.h>
 
+#include <string>
+
 #include "base/macros.h"
 
 namespace art {