Makefile: add USE_WILDMATCH to use wildmatch as fnmatch
This is similar to NO_FNMATCH but it uses wildmatch instead of
compat/fnmatch. This is an intermediate step to let wildmatch be used
as fnmatch replacement for wider audience before it replaces fnmatch
completely and compat/fnmatch is removed.
fnmatch in test-wildmatch is not impacted by this and is the only
place that NO_FNMATCH or NO_FNMATCH_CASEFOLD remain active when
USE_WILDMATCH is set.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>