When using multi-homed machines, it's nice to be able to specify
the local IP to use for outbound connections.  This patch gives
cifs the ability to bind to a particular IP address.

   Usage:  mount -t cifs -o srcaddr=192.168.1.50,user=foo, ...
   Usage:  mount -t cifs -o srcaddr=2002::100:1,user=foo, ...
Acked-by: NJeff Layton <jlayton@redhat.com>
Acked-by: NDr. David Holder <david.holder@erion.co.uk>
Signed-off-by: NBen Greear <greearb@candelatech.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>