Fix pp_send() sizes (pass a Size_t, not an Off_t, and

Fix pp_send() sizes (pass a Size_t, not an Off_t, and
return a SSize_t, not an Off_t); add a note about a slightly
similar situation in pp_truncate(); introduce $sizesize
for Configure; update EPOC, VOS, Win32, and VMS for the
sizesize; minor updates on the EPOC config file; reword
socklen_t message slightly; fix fpossize (though unused	currently)

p4raw-id: //depot/cfgperl@5760