Odd numbering of search results with mformat=mh about mairix

[ConradHughes]

.. on the face of it, all that seems to be needed to fix this appears to be changing the use of 'i' (database index number) to 'n_hits' in calls to mk_mh_path() in do_search().

[vandry]

I guess this might have been done so that the same email always gets the same filename in search results (as long as the index is not rebuilt). MUAs might recognise it as the same email after the search results mailbox has been cleared and reinitialized.

In any case your commit aa4ae41 resolves this.