check_c_source_compiles("
  #include <unistd.h>
  #include <sys/un.h>
  #include <sys/types.h>
  #include <sys/socket.h>
  int main() {
      int sock;
      sock = socket(AF_UNIX, SOCK_STREAM, 0);
      close(sock);
      return 0;
  }" FLB_HAVE_UNIX_SOCKET)