Update etc/rc.update_bogons.sh

The used version of sh does not support the fallthrough operator and function keyword.
Fix mac spoof when PPPoE is being used

When PPPoE is set and you change interface's mac address, the netgraph
node kept using the old parent interface mac address. Detach it before
attach on interface_ppps_configure() will make sure it is using the
current mac address.

It should fix #2641
Merge pull request #332 from bcyrill/patch-2

Update etc/rc.update_bogons.sh
Use sysctl for this since its better rather than going thorugh dmesg
Merge git pull request 313 from bcyrill with some modifications
Revert "When a interface type is changed, old configuration remains. When moving from static ip to ppp, it kepts the static ip configured on interface, when moving from ppp to static ip, it doesn't kill mpd. Implement interface_clean() to make sure only current configuration is in place"

This reverts commit 9111e5fd88f284bd6f66a24a270af9d9fea1b6c7.
Set flag setautosrc to replicate parent's mac address automatically when it changes, it's a better solution then dettach it. This should fix #2641
Missing return statement
Merge pull request #333 from bcyrill/missing_return

Missing return statement
Forgotten -n option