parse_pathspec: save original pathspec for reporting

We usually use pathspec_item's match field for pathspec error
reporting. However "match" (or "raw") does not show the magic part,
which will play more important role later on. Preserve exact user
input for reporting.

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

pathspec.h

@@ -16,6 +16,7 @@ struct pathspec {
 	int max_depth;
 	struct pathspec_item {
 		const char *match;
+		const char *original;
 		unsigned magic;
 		int len;
 		int nowildcard_len;