[RFC] load network config file from netif init script

Hello,

r272959 broke compatibility with mfsBSD that stores the default network
config file in /etc/rc.conf.d/network. In order to fix that load the
network config file from netif also.

I'm attaching a patch to restore previous functionality, but since I'm
not an expert on rc.d init scripts I would like some feedback on whether
this is the right approach or not.

Thanks, Roger.