libchromeos: more minijail wrappers

Added some more wrapper functions in libchromeos/minijail.
The two functions I added were to parse seccomp filters and
for minijail_enter

BUG=None
TEST=emerge-lumpy libchromeos

Change-Id: If917fd984a851e60eb1c7c6fbdafd84fb8aefa7c
Reviewed-on: https://chromium-review.googlesource.com/213218
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Tested-by: Utkarsh Sanghi <usanghi@chromium.org>
Commit-Queue: Utkarsh Sanghi <usanghi@chromium.org>
3 files changed