Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r228657:

In usr.sbin/bsnmpd/modules/snmp_wlan/wlan_snmp.h, use the correct
enumeration types for the mesh_peering and mesh_forwarding members of
struct wlan_iface, to fix enum conversion warnings.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Bring in a SNMP module to support monitoring cloned wireless interfaces
via bsnmpd(1). The module implements a private BEGEMOT-WIRELESS-MIB.

Sponsored by: The FreeBSD Foundation
Reviewed by: philip@
Approved by: philip@