cc -O2 -pipe -pthread  -Wall -Wextra -Werror=implicit-function-declaration semaphore/sem_clockwait.c -o semaphore/sem_clockwait -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread -lrt  -lstdthreads -lcrypt
semaphore/sem_clockwait.c:17:7: error: call to undeclared function 'sem_clockwait'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
   17 |         if ( sem_clockwait(&sem, CLOCK_MONOTONIC, &long_timeout) < 0 )
      |              ^
semaphore/sem_clockwait.c:17:7: note: did you mean 'sem_clockwait_np'?
/usr/include/semaphore.h:56:6: note: 'sem_clockwait_np' declared here
   56 | int      sem_clockwait_np(sem_t * __restrict, __clockid_t, int,
      |          ^
1 error generated.