propagating interface FIB to PCB

ed maste pointed me here after he saw me post the following on twixter:

<<anybody in freebsd land know why in{6,}_pcbbind() doesn't propagate 
the interface FIB to the PCB (assuming that's still zero)? i've got a 
multi-homed dual-FIB server that's failing BCP38 and this seems pretty 
crusty.>>

to be clear, i can fix this and submit a patch, but won't if there are 
reasons why it was kept this way.

-- 
P Vixie