Handle mounts under /run

We shouldn't excluded all volumes under /run since some distos will
mount filesystems there. Instead we should exclude all filesystems with
the type "tmpfs" that /run has, and rpc_pipefs that is mounted below
/run. Tmpfs" is excluded for all UNIX systems since the BSDs have
a similarly named filesystem.

Change-Id: I03fdac515c0bfb1b824b2e3eae1022dd699c0998
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>