zebra: Add link parameters support to Zebra

* zebra/interface.c:
   - Add new link-params CLI commands
   - Add new functions to set/get link parameters for interface
* zebra/redistribute.[c,h]: Add new function to propagate link parameters
  to routing daemon (essentially OSPFD and ISISD) for Traffic Engineering.
* zebra/redistribute_null.c: Add new function
  zebra_interface_parameters_update()
* zebra/zserv.[c,h]: Add new functions to send link parameters

Signed-off-by: Olivier Dugeon <olivier.dugeon@orange.com>
6 files changed