cmake HAVE_IB_GCC_ATOMIC_COMPARE_EXCHANGE examples

google/mysql-protobuf storage/innobase/innodb.cmake :154 

CHECK_C_SOURCE_RUNS(
  "#include<stdint.h>
  int main()
  {
    unsigned char	a = 0;
    unsigned char	b = 0;
    unsigned char	c = 1;

    __atomic_exchange(&a, &b,  &c, __ATOMIC_RELEASE);
    __atomic_compare_exchange(&a, &b, &c, 0,
			      __ATOMIC_RELEASE, __ATOMIC_ACQUIRE);
    return(0);
  }"
  HAVE_IB_GCC_ATOMIC_COMPARE_EXCHANGE
  )

google/mysql-protobuf storage/innobase/innodb.cmake :180 

ADD_DEFINITIONS(-DHAVE_IB_GCC_ATOMIC_COMPARE_EXCHANGE=1)