Variablizing

Apparently modifying comest->X as part of a check actually changes the
value displayed in the UI, so that's not such a good idea.  This moves
it to variables to avoid that problem as reported for Carnivore eating.
Gizzard will be handled in a separate commit.

Thanks to Belrend on the IRC for reporting.
Gizzard

Because bugs are *not* for the birds.
Merge pull request #8770 from KA101/foodfix

Fix comestible-cutting bug