xcb_discard_reply: Simplify by re-using poll_for_reply helper.
xcb_discard_reply: Simplify by re-using poll_for_reply helper.

If you discard a sequence number that has multiple responses already
read, this will do more allocations than necessary. But nobody cares
about ListFontsWithInfo.

Signed-off-by: Jamey Sharp <167c1dcbbc9c320e8e02a0c15c886204b4e658a4@minilop.net>

stapelberg/libxcb,stapelberg/libxcb,stapelberg/libxcb