Convert struct diff_options to use struct pathspec

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/diff.h b/diff.h
index 0083d92..310bd6b 100644
--- a/diff.h
+++ b/diff.h
@@ -133,9 +133,7 @@
 	FILE *file;
 	int close_file;
 
-	int nr_paths;
-	const char **paths;
-	int *pathlens;
+	struct pathspec pathspec;
 	change_fn_t change;
 	add_remove_fn_t add_remove;
 	diff_format_fn_t format_callback;