fs-util: use int for argument that takes F_OK and friends

access_nofollow() is a simple wrapper of faccessat(), and it is defined as
```
int faccessat(int dirfd, const char *pathname, int mode, int flags);
```

src/basic/fs-util.c

@@ -368,7 +368,7 @@ int fd_warn_permissions(const char *path, int fd) {
         return stat_warn_permissions(path, &st);
 }
 
-int access_nofollow(const char *path, mode_t mode) {
+int access_nofollow(const char *path, int mode) {
         return RET_NERRNO(faccessat(AT_FDCWD, path, mode, AT_SYMLINK_NOFOLLOW));
 }
 

src/basic/fs-util.h

@@ -39,7 +39,7 @@ int futimens_opath(int fd, const struct timespec ts[2]);
 int fd_warn_permissions(const char *path, int fd);
 int stat_warn_permissions(const char *path, const struct stat *st);
 
-int access_nofollow(const char *path, mode_t mode);
+int access_nofollow(const char *path, int mode);
 
 int touch_fd(int fd, usec_t stamp);
 int touch_file(const char *path, bool parents, usec_t stamp, uid_t uid, gid_t gid, mode_t mode);