gcc -pthread  -Wall -Wextra -Werror=implicit-function-declaration pthread/pthread_cond_clockwait.c -o pthread/pthread_cond_clockwait -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lxnet -lsocket -latomic
pthread/pthread_cond_clockwait.c: In function ‘main’:
pthread/pthread_cond_clockwait.c:20:23: error: implicit declaration of function ‘pthread_cond_clockwait’; did you mean ‘pthread_cond_timedwait’? [-Wimplicit-function-declaration]
   20 |         if ( (errno = pthread_cond_clockwait(&cnd, &mtx, CLOCK_MONOTONIC,
      |                       ^~~~~~~~~~~~~~~~~~~~~~
      |                       pthread_cond_timedwait