build_packages: drop --withevents

This gets passed to emerge which then ignores it.  We've dropped the
flag from chromite so no one should be using this anymore which means
we can drop it from here.

BUG=chromium:970829
TEST=CQ passes

Change-Id: Ib21e80ffb5000cc068e866f4558a95bc6518243e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/2080678
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
1 file changed