libcli/smb: fix BUFFER_OVERFLOW handling in tstream_smbXcli_np

libcli/smb: fix BUFFER_OVERFLOW handling in tstream_smbXcli_np

The special error is not NT_STATUS_BUFFER_TOO_SMALL, but STATUS_BUFFER_OVERFLOW.

Tested using TSTREAM_SMBXCLI_NP_MAX_BUF_SIZE == 20 and running
the following commands against a Windows 2012R2 server:

bin/smbtorture ncacn_np:SERVER[] rpc.lsa-getuser
bin/smbtorture ncacn_np:SERVER[smb2] rpc.lsa-getuser

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11623

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Tue Dec  1 03:42:52 CET 2015 on sn-devel-104