s3: libsmb: Reverse sense of 'clear all attributes', ignore attribute change in SMB2...

s3: libsmb: Reverse sense of 'clear all attributes', ignore attribute change in SMB2 to match SMB1.

SMB1 uses attr == 0 to clear all attributes
on a file (end up with FILE_ATTRIBUTE_NORMAL),
and attr == FILE_ATTRIBUTE_NORMAL to mean ignore
request attribute change.

SMB2 uses exactly the reverse. Unfortunately as the
cli_setatr() ABI is exposed inside libsmbclient,
we must make the SMB2 cli_smb2_setatr() call
export the same ABI as the SMB1 cli_setatr()
which calls it. This means reversing the sense
of the requested attr argument if it's zero
or FILE_ATTRIBUTE_NORMAL.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12899

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Richard Sharpe <realrichardsharpe@gmail.com>