gossipd: don't try to handle padding inside fromwire_ipaddr.

It makes it impossible to embed an ipaddr in another structure, since we
always try to skip over any zeroes, which may swallow a following field.

Do the skip specially for the case where we're parsing routing messages:
we never use padding for our own internal messages anyway.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

gossipd/routing.c

@@ -637,6 +637,10 @@ static struct ipaddr *read_addresses(const tal_t *ctx, const u8 *ser)
 	while (cursor && cursor < ser + max) {
 		struct ipaddr ipaddr;
 
+		/* Skip any padding */
+		while (max && cursor[0] == ADDR_TYPE_PADDING)
+			fromwire_u8(&cursor, &max);
+
 		/* BOLT #7:
 		 *
 		 * The receiving node SHOULD ignore the first `address