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