Replace the legacy __sync built-in functions with __atomic ones libunwind uses the built-in __sync_* functions which are deprecated by GCC and should be replaced by __atomic_* ones. See the official manuals [1]. . The legacy __sync functions do not require to specify the memory order but __atomic ones do, so we choose the strongest one: __ATOMIC_SEQ_CST. . We do this because __sync_fetch_and_add() is not supported on armel. . [1]: https://gcc.gnu.org/onlinedocs/gcc/_005f_005fsync-Builtins.html
