Until now, resizing the window why synth is running in ncurses mode
caused synth to hang (it would finish the builds it was working on
but the display wouldn't update and no new jobs would start).  This
was due to an unhandled exception thown by ncurses binding as a result
of the resize event, and now these are handled.

The mtree exclusion file was improved to allow these leftover info
directories to be ignored (as is done in poudriere.  Before only
info/dir was ignored, but the presence of "dir" prevented "info" from
being removed by pkg(8) upon deinstallation.

Now when a builder starts on a new package, the port origin will be
shown in the running log (before only the completion was logged.)