utils: use lstat() instead of stat() in ensure_file()

ensure_file() checks !S_ISLNK to reject symlinks as bind-mount
destinations, but uses stat() which follows symlinks. Since stat()
resolves the symlink before returning, S_ISLNK is never true for
valid symlinks, making the check dead code.

Use lstat() so the S_ISLNK check works as intended.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Dariush Wahdany <86673488+dwahdany@users.noreply.github.com>

Author: dwahdany

utils.c

@@ -513,7 +513,7 @@ ensure_file (const char *path,
      We're trying to set up a mount point for a non-directory, so any
      non-directory, non-symlink is acceptable - it doesn't necessarily
      have to be a regular file. */
-  if (stat (path, &buf) ==  0 &&
+  if (lstat (path, &buf) ==  0 &&
       !S_ISDIR (buf.st_mode) &&
       !S_ISLNK (buf.st_mode))
     return 0;