devserver: use emaint-$BOARD

The /usr/lib/portage/bin/emaint path no longer exists in recent portage
versions.  But rather than use the updated internal path, lets switch to
the existing emaint-$BOARD wrapper.

BUG=chromium:462099
TEST=`cbuildbot amd64-generic-full` passes w/new & old portage

Change-Id: Ia1ced6fdc4d5ef1cd6b6b9eee2bfc27cdf6f643f
Reviewed-on: https://chromium-review.googlesource.com/254681
Trybot-Ready: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
1 file changed