wildmatch: make wildmatch's return value compatible with fnmatch

wildmatch: make wildmatch's return value compatible with fnmatch

wildmatch returns non-zero if matched, zero otherwise. This patch
makes it return zero if matches, non-zero otherwise, like fnmatch().

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
Signed-off-by: Junio C Hamano <redacted>