verity: upgrade to new common.mk format

Migrates the Makefile format and module.mk to use the
newest common.mk. This also fixes link ordering (thanks vapier@)

Signed-off-by: Will Drewry <wad@chromium.org>

TEST=emerge-x86-alex verity, FEATURES=test emerge-x86-alex verity
BUG=None

Change-Id: I09e80e7730208e5c614bc93fe6348ab652703988
Reviewed-on: https://gerrit.chromium.org/gerrit/15853
Reviewed-by: Sonny Rao <sonnyrao@chromium.org>
Tested-by: Will Drewry <wad@chromium.org>
Commit-Ready: Will Drewry <wad@chromium.org>
4 files changed