streaming: mark unused virtual method parameters

Streaming "open" functions need to conform to the same virtual function
interface, but not every implementation needs every parameter. Mark the
unused ones as such to appease -Wunused-parameter.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

streaming.c

@@ -328,9 +328,9 @@ static int close_istream_pack_non_delta(struct git_istream *st)
 }
 
 static int open_istream_pack_non_delta(struct git_istream *st,
-				       struct repository *r,
-				       const struct object_id *oid,
-				       enum object_type *type)
+				       struct repository *UNUSED(r),
+				       const struct object_id *UNUSED(oid),
+				       enum object_type *UNUSED(type))
 {
 	struct pack_window *window;
 	enum object_type in_pack_type;