Make explicit draining the socket on RECVFILE. Add

Make explicit draining the socket on RECVFILE. Add
capability for large UNIX write if not signing and
recvfile set. Cope with large UNIX write length on
incoming processing. Stevef - we can now test 1-16Mb
writes from CIFFS.
Jeremy.
(This used to be commit 8cf78776b0a44bd026cef3d74eb11cfb415f8303)