ref-filter: add option to match literal pattern

Since 'ref-filter' only has an option to match path names add an
option for plain fnmatch pattern-matching.

This is to support the pattern matching options which are used in `git
tag -l` and `git branch -l` where we can match patterns like `git tag
-l foo*` which would match all tags which has a "foo*" pattern.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

ref-filter.h

@@ -59,7 +59,8 @@ struct ref_filter {
 	} merge;
 	struct commit *merge_commit;
 
-	unsigned int with_commit_tag_algo : 1;
+	unsigned int with_commit_tag_algo : 1,
+		match_as_path : 1;
 	unsigned int kind,
 		lines;
 };