pathspec: save the non-wildcard length part

We mark pathspec with wildcards with the field use_wildcard. We
could do better by saving the length of the non-wildcard part, which
can be used for optimizations such as f9f6e2c (exclude: do strcmp as
much as possible before fnmatch - 2012-06-07).

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -482,7 +482,7 @@ struct pathspec {
 	struct pathspec_item {
 		const char *match;
 		int len;
-		unsigned int use_wildcard:1;
+		int nowildcard_len;
 	} *items;
 };