compositor-drm: Fix setting O_CLOEXEC
compositor-drm: Fix setting O_CLOEXEC

The third parameter of open() is for file-creation modes. File flags are passed
in the second paramater.

Signed-off-by: David Herrmann <fb53b2ddb8d141e0cb39d7c67c2f81b6bc2eb0f7@googlemail.com>

krezovic/weston,giucam/weston,Tarnyko/weston-xdg_surface_present,mchalupa/weston,jonnylamb/weston,krezovic/weston,Fantu/compositor-spice,udoprog/weston,mchalupa/weston,Gnurou/weston,kwm81/weston,xorgy/weston,kwm81/weston,Fantu/compositor-spice,giucam/weston,sir-murray/weston,eyolfson/weston,Gnurou/weston,Fantu/compositor-spice,xorgy/weston,udoprog/weston,sir-murray/weston,eyolfson/weston,Tarnyko/weston-xdg_surface_present,jonnylamb/weston