tests: silence warnings from pipe()
tests: silence warnings from pipe()

warning: ignoring return value of ‘pipe’, declared with attribute
warn_unused_result

Signed-off-by: Pekka Paalanen <6c0263d81461c956d504307112a4ce25eaacc3d1@gmail.com>

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