Don't define NVLAN - vlan support is currently ``#if 0'' in if_igc.c

if_igc needs WARNS=3

Define NVLAN for consistency with if_alc and if_aq modules

Add MODULE glue and build infrasructure.

XXX We won't actually build or install it due to kern/59716 but
XXX it can be manually built and installed if you want.

Add MODULE glue and build infrasructure.

XXX We won't actually build or install it due to kern/59716 but
XXX it can be manually built and installed if you want.