lib/io_udp.t fails on VMS

lib/io_udp.t fails on VMS

perl 5.004 built without error or warning on VMS AXP/DECC with DECCRTL
(UCX) sockets (no sockshr library). However it fails the
lib/io_udp.t test for the following reasons:

1. The 'fromlen' parameter in pp_sysread *must* be sizeof(struct
   sockaddr) or the DECCRTL fails with an invalid buffer size error.

2. The DECCRTL/UCX getpeerhost() function returns defined and a blank
   'sockaddr' for udp hosts. A similar fix to that in vms/sockadapt.h
   (for sockshr) is required for DECCRTL in pp_sys.c

The following diff (unix, sorry VMS folks) patches pp_sys.c so that
the udp test is successful using UCX.

p5p-msgid: XFMail.970522181042.Jonathan.Hudson@jrhudson.demon.co.uk