Add ability to put jailed process in cgroups

This adds an API that allows the jailed process to be added to a given
cgroup.  This API can be called repeatedly to add the process to many
cgroups.  The process will be added after fork but before it is exec'd.

BUG=b/26549867
TEST=set cgroups and inspect that pid is in tasks file

Change-Id: I87a9897c1dc741c726873e872eeae32692088979
Signed-off-by: Dylan Reid <dgreid@chromium.org>
2 files changed