cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations unistd/_SC_NSIG.c -o unistd/_SC_NSIG -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt -lcrypt -latomic
unistd/_SC_NSIG.c:2:17: error: ‘_SC_NSIG’ undeclared here (not in a function)
    2 | int const foo = _SC_NSIG;
      |                 ^~~~~~~~