Prepare ground for extensions to sFlow export. Standard LACP
 counters are added to the LACP module, and the sFlow
 library and test modules are extended to support the export
 of those LACP counters as well as tunnel and OpenFlow
 related structures. None of these structures are actually
 exported yet,  so this patch should have no discernible
 effect. Hence no changes to the unit tests.

Signed-off-by: Neil McKee <neil.mckee@inmon.com>