eclass: Drop unused eclasses

These being present makes determining what other cleanups are possible
more difficult.

BUG=none
TEST=CQ passes

Change-Id: I9e825d3149fc4d8e3ebcc22067b2ac2ac99e076f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/3913267
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Matt Turner <msturner@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Auto-Submit: Matt Turner <msturner@google.com>
121 files changed