netfilter: fix warning in net/netfilter/nf_conntrack_ftp.c

this warning:

  net/netfilter/nf_conntrack_ftp.c: In function 'help':
  net/netfilter/nf_conntrack_ftp.c:360: warning: 'matchoff' may be used uninitialized in this function
  net/netfilter/nf_conntrack_ftp.c:360: warning: 'matchlen' may be used uninitialized in this function

triggers because GCC does not recognize the (correct) error flow
between find_pattern(), 'found', 'matchoff' and 'matchlen'.

Annotate it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/netfilter/nf_conntrack_ftp.c

@@ -358,7 +358,7 @@ static int help(struct sk_buff *skb,
 	int ret;
 	u32 seq;
 	int dir = CTINFO2DIR(ctinfo);
-	unsigned int matchlen, matchoff;
+	unsigned int uninitialized_var(matchlen), uninitialized_var(matchoff);
 	struct nf_ct_ftp_master *ct_ftp_info = &nfct_help(ct)->help.ct_ftp_info;
 	struct nf_conntrack_expect *exp;
 	union nf_inet_addr *daddr;