qxl: Add missing GCC_FMT_ATTR and fix format specifier val is an uint64_t, therefore %d was not correct. Signed-off-by: Stefan Weil <sw@weilnetz.de> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>