Do a pass over all the engines upon starting to determine the global
scheduler capability flags (those that are agreed upon by all).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190226102404.29153-7-chris@chris-wilson.co.uk