netfilter: Fix switch statement warnings with recent gcc.

More recent GCC warns about two kinds of switch statement uses:

1) Switching on an enumeration, but not having an explicit case
   statement for all members of the enumeration.  To show the
   compiler this is intentional, we simply add a default case
   with nothing more than a break statement.

2) Switching on a boolean value.  I think this warning is dumb
   but nevertheless you get it wholesale with -Wswitch.

This patch cures all such warnings in netfilter.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_compat.c

@@ -321,11 +321,11 @@ static void nft_match_eval(const struct nft_expr *expr,
 		return;
 	}
 
-	switch(ret) {
-	case true:
+	switch (ret ? 1 : 0) {
+	case 1:
 		data[NFT_REG_VERDICT].verdict = NFT_CONTINUE;
 		break;
-	case false:
+	case 0:
 		data[NFT_REG_VERDICT].verdict = NFT_BREAK;
 		break;
 	}

net/netfilter/nft_ct.c

@@ -56,6 +56,8 @@ static void nft_ct_get_eval(const struct nft_expr *expr,
 			state = NF_CT_STATE_BIT(ctinfo);
 		dest->data[0] = state;
 		return;
+	default:
+		break;
 	}
 
 	if (ct == NULL)
@@ -117,6 +119,8 @@ static void nft_ct_get_eval(const struct nft_expr *expr,
 		return;
 	}
 #endif
+	default:
+		break;
 	}
 
 	tuple = &ct->tuplehash[priv->dir].tuple;
@@ -141,6 +145,8 @@ static void nft_ct_get_eval(const struct nft_expr *expr,
 	case NFT_CT_PROTO_DST:
 		dest->data[0] = (__force __u16)tuple->dst.u.all;
 		return;
+	default:
+		break;
 	}
 	return;
 err:
@@ -172,6 +178,8 @@ static void nft_ct_set_eval(const struct nft_expr *expr,
 		}
 		break;
 #endif
+	default:
+		break;
 	}
 }