systemd PR

int write_string_file_full(int dir_fd, const char *fn, const char *line, WriteStringFileFlags flags, const struct timespec *ts, const char *label_fn);
static inline int write_string_file(const char *fn, const char *line, WriteStringFileFlags flags) {
        return write_string_file_full(AT_FDCWD, fn, line, flags, /* ts= */ NULL, /*label_fn=*/ NULL);
}
static inline int write_string_file_label(const char *fn, const char *line, WriteStringFileFlags flags, const char *label_fn) {
        return write_string_file_full(AT_FDCWD, fn, line, flags, /* ts= */ NULL, label_fn);
}