Remove legacy __sync builtins

The legacy gcc builtin "__sync_fetch_and_add" was replaced with
"__atomic_fetch_add (__ATOMIC_SEQ_CST)" to ensure total ordering
with all other __ATOMIC_SEQ_CST operations.

Signed-off-by: Chun-Hung Tseng <henrybear327@gmail.com>

Author: henrybear327

qsbr/main.c

@@ -5,7 +5,7 @@
 #define unlikely(x) __builtin_expect((x) != 0, 0)
 
 #ifndef atomic_fetch_add
-#define atomic_fetch_add(x, a) __sync_fetch_and_add(x, a)
+#define atomic_fetch_add(x, a) __atomic_fetch_add(x, a, __ATOMIC_SEQ_CST)
 #endif
 
 #ifndef atomic_thread_fence