Final part of fix for bug #8679 - recvfile code path using splice() on Linux leaves...

Final part of fix for bug #8679 - recvfile code path using splice() on Linux leaves data in the pipe on short write.

The code to set a DOS error on short writeX return is amazingly
legacy code, and also breaks the reply as fixup_chain_error_packet()
enforces a 2-byte wct on any reply where smb_rcls != 0.

Found in testing by Andrew Bartlett. Thanks Andrew !

Autobuild-User: Jeremy Allison <jra@samba.org>
Autobuild-Date: Sat Dec 31 08:05:35 CET 2011 on sn-devel-104
(cherry picked from commit e39df67669f61056692736db9c8dc16fbf2c3624)