Run eclean by default to clear out binary packages in case of a revert.

This adds eclean early in make_chroot, update_chroot, and
build_packages to clear out binary packages that correspond to ebuilds
that have been removed or reverted.

TEST=CQ passes

Change-Id: Ie519aa547bb63743375d4fd9b83d1b11f0ef11ff
Tested-by: Allen Webb <>
Reviewed-by: Mike Frysinger <>
Commit-Queue: Allen Webb <>
3 files changed