wildmatch: rename constants and update prototype

- All exported constants now have a prefix WM_
- Do not rely on FNM_* constants, use the WM_ counterparts
- Remove TRUE and FALSE to follow Git's coding style
- While at it, turn flags type from int to unsigned int
- Add an (unused yet) argument to carry extra information
  so that we don't have to change the prototype again later
  when we need to pass other stuff to wildmatch

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

test-wildmatch.c

@@ -12,9 +12,9 @@ int main(int argc, char **argv)
 			argv[i] += 3;
 	}
 	if (!strcmp(argv[1], "wildmatch"))
-		return !!wildmatch(argv[3], argv[2], 0);
+		return !!wildmatch(argv[3], argv[2], 0, NULL);
 	else if (!strcmp(argv[1], "iwildmatch"))
-		return !!wildmatch(argv[3], argv[2], FNM_CASEFOLD);
+		return !!wildmatch(argv[3], argv[2], WM_CASEFOLD, NULL);
 	else if (!strcmp(argv[1], "fnmatch"))
 		return !!fnmatch(argv[3], argv[2], FNM_PATHNAME);
 	else