Fix xp_raddr handling in svc_fd_create etc

Fix xp_raddr handling in svc_fd_create etc

Currently svc_fd_create tries to do some clever tricks
with IPv4/v6 address mapping.

This is broken for several reasons.
 1.	We don't want IPv4 based transport to look like IPv6
 	transports. Old applications compiled against tirpc
	will expect AF_INET addresses, and are not equipped
	to deal with AF_INET6.
 2.	There's a buffer overflow.
		memcpy(&sin6, &ss, sizeof(ss));
	copies a full struct sockaddr to a sockaddr_in6 on
	the stack. Unlikely to be exploitable, but I wonder
	if this ever worked....

Signed-off-by: Olaf Kirch <okir@suse.de>
Signed-off-by: Steve Dickson <steved@redhat.com>