launcher/version: include OS/CPU info in output

We often ask users what OS/version they're running when debugging.
Include that in the version output to simplify the process.

Change-Id: Ie480b6d1c874e6f4c6f4996a03795077b844f858
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/256732
Reviewed-by: David Pursehouse <dpursehouse@collab.net>
Tested-by: Mike Frysinger <vapier@google.com>