Various tidy ups, add LIKELY/UNLIKELY macros.

Make more aggressive use of the dex cache when we have it.

Change-Id: I125a7bac031f7f0cec68194b5380bdfd83c92833
diff --git a/src/macros.h b/src/macros.h
index 9c5124b..f016f9e 100644
--- a/src/macros.h
+++ b/src/macros.h
@@ -125,4 +125,7 @@
 
 #define PACKED __attribute__ ((__packed__))
 
+#define LIKELY(x)       __builtin_expect((x),true)
+#define UNLIKELY(x)     __builtin_expect((x),false)
+
 #endif  // ART_SRC_MACROS_H_