wildmatch: remove unused wildopts parameter

wildmatch: remove unused wildopts parameter

Remove the unused wildopts placeholder struct from being passed to all
wildmatch() invocations, or rather remove all the boilerplate NULL
parameters.

This parameter was added back in commit 9b3497cab9 ("wildmatch: rename
constants and update prototype", 2013-01-01) as a placeholder for
future use. Over 4 years later nothing has made use of it, let's just
remove it. It can be added in the future if we find some reason to
start using such a parameter.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>