FreeBSD (and maybe other BSDs) have different member
names in struct ifreq when compared to Linux, such as:

 - uses ifr_data instead of ifr_newname for setting
   interface names
 - uses ifr_index instead of ifr_ifindex for interface
   index

Also, add a check for SIOCGIFHWADDR for virNetDevValidateConfig().

Use AF_LOCAL if AF_PACKET is not available.
Signed-off-by: NEric Blake <eblake@redhat.com>