netfilter: xtables: change targets to return error code

Part of the transition of done by this semantic patch:
// <smpl>
@ rule1 @
struct xt_target ops;
identifier check;
@@
 ops.checkentry = check;

@@
identifier rule1.check;
@@
 check(...) { <...
-return true;
+return 0;
 ...> }

@@
identifier rule1.check;
@@
 check(...) { <...
-return false;
+return -EINVAL;
 ...> }
// </smpl>

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c
index c1553bf..ee566e2 100644
--- a/net/netfilter/xt_CT.c
+++ b/net/netfilter/xt_CT.c
@@ -62,7 +62,7 @@
 	u8 proto;
 
 	if (info->flags & ~XT_CT_NOTRACK)
-		return false;
+		return -EINVAL;
 
 	if (info->flags & XT_CT_NOTRACK) {
 		ct = &nf_conntrack_untracked;
@@ -108,14 +108,14 @@
 	__set_bit(IPS_CONFIRMED_BIT, &ct->status);
 out:
 	info->ct = ct;
-	return true;
+	return 0;
 
 err3:
 	nf_conntrack_free(ct);
 err2:
 	nf_ct_l3proto_module_put(par->family);
 err1:
-	return false;
+	return -EINVAL;
 }
 
 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par)