cc -O2 -pipe -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  -lstdthreads -lcrypt
unistd/_PC_FALLOC.c:2:17: error: use of undeclared identifier '_PC_FALLOC'
    2 | int const foo = _PC_FALLOC;
      |                 ^
1 error generated.