cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration signal/sigwaitinfo.c -o signal/sigwaitinfo -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
signal/sigwaitinfo.c: In function ‘main’:
signal/sigwaitinfo.c:22:14: error: implicit declaration of function ‘sigqueue’ [-Wimplicit-function-declaration]
   22 |         if ( sigqueue(getpid(), SIGUSR1, sv) < 0 )
      |              ^~~~~~~~
signal/sigwaitinfo.c:24:14: error: implicit declaration of function ‘sigwaitinfo’ [-Wimplicit-function-declaration]
   24 |         if ( sigwaitinfo(&set, &info) < 0 )
      |              ^~~~~~~~~~~