client: Don't cancel a roundtrip when any event is received
client: Don't cancel a roundtrip when any event is received

Since wl_display_dispatch() returns the number of processed events or -1
on error, only cancel the roundtrip if an -1 is returned.

This also fixes a potential memory corruption bug happening when
wl_display_roundtrip() does an early return and the callback later
writes to the then out of scope stack allocated `done' parameter.

Introduced by 33b7637b4500a682018b503837b8aca9afae36f2.

Signed-off-by: Jonas Ådahl <67dcd8a17e758192e0cbb577ce1d62cc7da6cf49@gmail.com>

sir-murray/wayland,bitfactor/wayland,bitfactor/wayland,sir-murray/wayland,tulcod/wayland,abooij/wayland,eyolfson/wayland,tulcod/wayland,abooij/wayland,abooij/wayland,tulcod/wayland,mchalupa/wayland,mchalupa/wayland,sir-murray/wayland,eyolfson/wayland,eyolfson/wayland,bitfactor/wayland,mchalupa/wayland