cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations stdlib/O_RSYNC.c -o stdlib/O_RSYNC -D_POSIX_C_SOURCE=202405L  -lm -lpthread  -liconv
stdlib/O_RSYNC.c:3:17: error: use of undeclared identifier 'O_RSYNC'
    3 | int const foo = O_RSYNC;
      |                 ^
1 error generated.