scons: Add coroutines component to build.

Fixes: d32690b4 ("gallivm: add coroutine pass manager support")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Dave Airlie <airlied@redhat.com>
22 jobs for !1866 with fix-scons-coroutine in 15 minutes and 43 seconds (queued for 2 seconds)
merge request