Don't echo from the InstallationCheck script

Don't echo from the InstallationCheck script

Return codes from InstallationCheck are turned into errors by
the GUI - don't echo them out to stdout as well.

Change-Id: Iee9c1ff4687ea42ab8c18566493a8a92b6d51fed
Reviewed-on: http://gerrit.openafs.org/1206
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit c0724584680562330347026ee9ec72f74066bc51)
Reviewed-on: http://gerrit.openafs.org/1207