Import the 'iflib' API library for network drivers. From the author:

Import the 'iflib' API library for network drivers.  From the author:

"iflib is a library to eliminate the need for frequently duplicated device
independent logic propagated (poorly) across many network drivers."

Participation is purely optional.  The IFLIB kernel config option is
provided for drivers that want to transition between legacy and iflib
modes of operation.  ixl and ixgbe driver conversions will be committed
shortly.  We hope to see participation from the Broadcom and maybe
Chelsio drivers in the near future.

Submitted by:   mmacy@nextbsd.org
Reviewed by:    gallatin
Differential Revision:  D5211