After writing a kernel core dump into /var/crash, call sync(8).

If we panic again shortly after boot (say, within 30 seconds), any core
dump we wrote out may be lost on reboot.  In this situation, we really
want to keep that core file, as it may be the only way to have the issue
resolved.  Call sync(8) after writing out the core file and running
crashinfo(8), in the hope that these will not be lost if we panic
again.  sync(8) is only called in the case where there is a core dump
to be written out, so won't be called during normal boots.

Discovered by:	Trying to debug an IPSEC panic
MFC after:	1 week

etc/rc.d/savecore

@@ -70,6 +70,7 @@ savecore_start()
 		if checkyesno crashinfo_enable; then
 			${crashinfo_program} -d ${dumpdir}
 		fi
+		sync
 	else
 		check_startmsgs && echo 'No core dumps found.'
 	fi