Drop a pair of parantheses from likely/unlikely

Such that "if likely(...)" wouldn't compile.

src/hb.hh

@@ -255,8 +255,8 @@ extern "C" void  hb_free_impl(void *ptr);
 #endif
 
 #if defined(__OPTIMIZE__) && hb_has_builtin(__builtin_expect)
-#define likely(expr) (__builtin_expect (bool(expr), 1))
-#define unlikely(expr) (__builtin_expect (bool(expr), 0))
+#define likely(expr) __builtin_expect (bool(expr), 1)
+#define unlikely(expr) __builtin_expect (bool(expr), 0)
 #else
 #define likely(expr) (expr)
 #define unlikely(expr) (expr)