mpm: run engines as few times as possible

mpm: run engines as few times as possible

In various scenarios buffers would be checked my MPM more than
once. This was because the buffers would be inspected for a
certain progress value or higher.

For example, for each packet in a file upload, the engine would
not just rerun the 'http client body' MPM on the new data, it
would also rerun the method, uri, headers, cookie, etc MPMs.

This was obviously inefficent, so this patch changes the logic.

The patch only runs the MPM engines when the progress is exactly
the intended progress. If the progress is beyond the desired
value, it is run once. A tracker is added to the app layer API,
where the completed MPMs are tracked.

Implemented for HTTP, TLS and SSH.