fusefrontend: fix fd leak in dirCache
fusefrontend: fix fd leak in dirCache

The missing break meant that we may find a second
hit in the cache, Dup() a second fd, and leak the first
one.

Thanks @slackner for finding this.

rfjakob/gocryptfs,rfjakob/gocryptfs,rfjakob/gocryptfs,rfjakob/gocryptfs