display-test: test if threads are woken up on EAGAIN
display-test: test if threads are woken up on EAGAIN

When wl_connection_read() in wl_display_read_events() returns with EAGAIN,
we want the sleeping threads to be woken up. Test it!

Signed-off-by: Marek Chalupa <a05df156a69ad59faa9af9b666ef78009594c145@gmail.com>
Reviewed-by: Pekka Paalanen <0f6ae7001e34c37b02fb2c1c2573ddf8f442136a@collabora.co.uk>

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