MFC r256689 (modified):
  Use the same actor key for media types of the same speed.

  PR:		176097

MFC r256832:
  Add a note that lacp_compose_key() should be updated, when new media
  types will be added.

  Submitted by:	melifaro
MFC r257084:
  Initialize inc_fibnum for properly handling ICMP6_PACKET_TOO_BIG
  errors in multifib environment.

  PR:		183265