cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations fcntl/F_OWNER_PID.c -o fcntl/F_OWNER_PID -D_POSIX_C_SOURCE=202405L  -lm -lpthread  -liconv
fcntl/F_OWNER_PID.c:2:17: error: use of undeclared identifier 'F_OWNER_PID'
    2 | int const foo = F_OWNER_PID;
      |                 ^
1 error generated.