Use Sys::Filesystem to determine container_depot_mount_point
Use Sys::Filesystem to determine container_depot_mount_point

The '%m' format specifier is not available on all versions of stat.

Change-Id: I0164aaa2c4f3b59188dd7d3f2febdda65f846e02

shashidharatd/garden-linux,tangfeixiong/garden,tsaleh/garden,tsaleh/garden,shashidharatd/garden-linux,cloudfoundry-incubator/garden-linux,cloudfoundry-incubator/garden,shashidharatd/garden-linux,cloudfoundry-incubator/garden,savaki/garden,savaki/garden,cloudfoundry-incubator/garden-linux,tangfeixiong/garden,cloudfoundry-incubator/garden-linux,shashidharatd/garden-linux