Atomic内置函数缺失

[Jules-Kong]

• 用例：CTS/c11_atomics

• 复现过程
  spike分支：feature/vector-amo
  pocl分支：fix-atomics

• 现象
  atomic_exchange
  

• 涉及用例

atomic_init
atomic_exchange
atomic_fetch_exchange_weak
atomic_fetch_exchange_strong
atomic_fetch_add
atomic_fetch_sub
atomic_fetch_orand
atomic_fetch_xor2
atomic_fetch_min
atomic_fetch_max
atomic_flag