Add libchromeos-minijail target.

Also fix a bunch of comments. "Target" in this context does not
refer to the build target (e.g 'libchromeos') but to the fact that
it's building *for* the target architecture (e.g. ARM) and not for
the host.

Bug: 22557394
Change-Id: Icabcb28809a46b74c3d5b4e8bd1975dda684598a
2 files changed