This is really, really slow at the moment for a few reasons:
- it goes through the list of revisions twice
- it checks many more revisions than it needs to
Even after these improvements it's still by far the slowest audit so
am also making it a `--git` only audit.
Additionally, to further improve default `brew audit` performance do not
run `brew style` checks when doing `brew audit` with no arguments.
`brew style` can be run quickly and efficiently on all of a tap (and is
cached) so no need to duplicate it here.
2a94d382ac