[Dovecot] patch for mysterious maildir symlink error

[Mike Abbott]

This may resolve the mysterious "Maildir: Symlink destination doesn't exist" 
errors.

--- a/src/lib-storage/index/maildir/maildir-util.c
+++ b/src/lib-storage/index/maildir/maildir-util.c
@@ -91,7 +91,7 @@
 {
        struct stat st;
 
-       if (lstat(path, &st) == 0 && (st.st_mode & S_IFLNK) != 0) {
+       if (lstat(path, &st) == 0 && (st.st_mode & S_IFMT) == S_IFLNK) {
                /* most likely a symlink pointing to a nonexistent file */
                mail_storage_set_critical(&mbox->storage->storage,
                        "Maildir: Symlink destination doesn't exist: %s", path);