dir.c: remove dead function fnmatch_icase()

It was largely replaced by fnmatch_icase_mem() and its last use was in
84b8b5d (remove match_pathspec() in favor of match_pathspec_depth() -
2013-07-14).

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

dir.c

@@ -64,13 +64,6 @@ int strncmp_icase(const char *a, const char *b, size_t count)
 	return ignore_case ? strncasecmp(a, b, count) : strncmp(a, b, count);
 }
 
-int fnmatch_icase(const char *pattern, const char *string, int flags)
-{
-	return wildmatch(pattern, string,
-			 flags | (ignore_case ? WM_CASEFOLD : 0),
-			 NULL);
-}
-
 int git_fnmatch(const struct pathspec_item *item,
 		const char *pattern, const char *string,
 		int prefix)

dir.h

@@ -272,7 +272,6 @@ extern int remove_path(const char *path);
 
 extern int strcmp_icase(const char *a, const char *b);
 extern int strncmp_icase(const char *a, const char *b, size_t count);
-extern int fnmatch_icase(const char *pattern, const char *string, int flags);
 
 /*
  * The prefix part of pattern must not contains wildcards.