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  -liconv
signal/sigwaitinfo.c:22:7: error: call to undeclared function 'sigqueue'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   22 |         if ( sigqueue(getpid(), SIGUSR1, sv) < 0 )
      |              ^
signal/sigwaitinfo.c:24:7: error: call to undeclared function 'sigwaitinfo'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   24 |         if ( sigwaitinfo(&set, &info) < 0 )
      |              ^
2 errors generated.