a pointer to the file system.
Renamed all static g* variables to s*.
Renamed "mount_id" fields to the higher level "device" (to be able
to compile the file).
Fixed all casting warnings.
git-svn-id: file:///srv/svn/repos/haiku/trunk/current@5077 a95241bf-73f2-0310-859d-f6bbb57e9c96