kernel/disk_device_manager: Use addr_t in UserDataWriter. This code was not touched since 2005, and even then, that was just a file rename. So it seems it simply predates addr_t.
Renamed system/core to system/kernel. git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12360 a95241bf-73f2-0310-859d-f6bbb57e9c96