源码编译opencv3.4.3 出错：undefined reference to `google::protobuf::internal::Release_CompareAndSwap

打开 protobuf/src/google/protobuf/stubs/atomicops_internals_generic_gcc.h
在下面添加：

inline Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr,
                                      Atomic64 old_value,
                                      Atomic64 new_value) {
  __atomic_compare_exchange_n(ptr, &old_value, new_value, false,
                              __ATOMIC_RELEASE, __ATOMIC_ACQUIRE);
  return old_value;
}