add likely / unlikely macros

include/jemalloc/internal/util.h

@@ -27,6 +27,14 @@
 #  define JEMALLOC_CC_SILENCE_INIT(v)
 #endif
 
+#ifdef __GNUC__
+#define likely(x) __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+#else
+#define likely(x) !!(x)
+#define unlikely(x) !!(x)
+#endif
+
 /*
  * Define a custom assert() in order to reduce the chances of deadlock during
  * assertion failure.