name-rev: drop unused parameters from is_better_name()

name-rev: drop unused parameters from is_better_name()

When this function was extracted in 0041bf6544 (name-rev: refactor logic
to see if a new candidate is a better name, 2017-03-29), it ended up
getting more arguments than it needs.

It's possible we may later use these values to evaluate the name, but
since it's a static function with a single caller, it will be easy to
add them back then.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>