cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration signal/sigtimedwait.c -o signal/sigtimedwait -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
signal/sigtimedwait.c: In function ‘main’:
signal/sigtimedwait.c:22:14: error: implicit declaration of function ‘sigtimedwait’ [-Wimplicit-function-declaration]
   22 |         if ( sigtimedwait(&set, &info, &delay) < 0 )
      |              ^~~~~~~~~~~~
signal/sigtimedwait.c:32:14: error: implicit declaration of function ‘sigqueue’ [-Wimplicit-function-declaration]
   32 |         if ( sigqueue(getpid(), SIGUSR1, sv) < 0 )
      |              ^~~~~~~~