Include <sys/ktr.h>, since we need it if ATH_DEBUG is defined.
Style: s/SYS_EVENTHANDLER_H/_SYS_EVENTHANDLER_H_/g

Submitted by:	bde
Fix compilation if SCTP_DONT_DO_PRIVADDR_SCOPE is defined.
The issue was reported by Andrew Galante.

MFC after: 3 days
G/c unused mountrootfsname.
It was replaced with rootdevnames in r52778.
[automated] Merge in upstream-github/master