Install the correct kernel "extra" modules on Ubuntu 15.10 slaves.
Install the correct kernel "extra" modules on Ubuntu 15.10 slaves.

The old code broke if the running kernel version was different than the latest installed one (e.g. after apt-get upgrade installed a new kernel during reimaging).

Change-Id: I97316ae84246e3c8b6fe7700b6b922d21b56a4dd

bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration