libminijail_unittest: add some tests

Adds libminijail_unittest with some very basic tests. More tests will
be added, but this gets all the pieces in place.

TEST=itself! [ FEATURES="test noclean" emerge-x86-alex chromeos-minijail ]
BUG=chromium-os:20917

Change-Id: I5893c6f72d1e741dd6287acde52af65500b059e4
Reviewed-on: http://gerrit.chromium.org/gerrit/8371
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Elly Jones <ellyjones@chromium.org>
Tested-by: Will Drewry <wad@chromium.org>
2 files changed