MFC r283291: don't use CALLOUT_MPSAFE with callout_init()The main purpose of this MFC is to reduce conflicts for other merges.Parts of the original change have already "trickled down" via individual MFCs.
MFC 277709:Use an sbuf to generate the output of the net.inet.tcp.hostcache.listsysctl to avoid a possible buffer overflow if the cache grows while thetext is being generated.PR: 172675