smb: protocol detection on pattern without midstream

smb: protocol detection on pattern without midstream

To recognize a protocol, Suricata first looks for
patterns, which can be confirmed by a probing parser.
If this does not work, Suricata can try to run
some probing parsers on some ports.

This is the case for SMB.

This commit makes handling the confirming and the probing
paser differently even if they share much code.

The confirmation parser knows that a pattern has been found.
So, it must not do the midstream case of looking for this
pattern in the whole buffer, but only check it at the beginning.
But it must reverse direction if needed.