to retrieve the default settings for the netmask/broadcast depending on the
specified address/netmask.
* interface_protocol_control() now uses this to reset the broadcast/netmask
to their default values on SIOCSIFADDR resp. the former only on
SIOCSIFNETMASK.
* This fixes bug #1861.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24170 a95241bf-73f2-0310-859d-f6bbb57e9c96