Remove a check in udp6_send() that prevented v4-mapped v6 addresses from working.  We store v4 and v6 addresses as a union but for v4-mapped addresses only store the 32bits w/o the ::ffff: word.  That failed the check as for example 127.0.0.1 would be ::7f00:1 rather than ::ffff:7f00:1 and the IN6_IS_ADDR_V4MAPPED() never worked here.  Given we can hardly get here with an unbound local address or invalid inp_vflags remove the check.
Remove a check in udp6_send() that prevented v4-mapped v6 addresses from
working.  We store v4 and v6 addresses as a union but for v4-mapped
addresses only store the 32bits w/o the ::ffff: word.  That failed the
check as for example 127.0.0.1 would be ::7f00:1 rather than ::ffff:7f00:1
and the IN6_IS_ADDR_V4MAPPED() never worked here.  Given we can hardly get
here with an unbound local address or invalid inp_vflags remove the check.

Reported by:	tuexen
Reviewed by:	tuexen
MFC after:	3 days

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase