s3: smbclient: Stop an SMB2-connection from blundering into SMB1-specific calls.

s3: smbclient: Stop an SMB2-connection from blundering into SMB1-specific calls.

Fix in the same way this was done in SMBC_opendir_ctx() for libsmbclient.
This fix means the admin no longer has to remember to set 'min client protocol ='
when connecting to an SMB2-only server (MacOSX for example) and trying to
list shares.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14152

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>