VBox broken after stack guard update

[AN]

FreeBSD FBSD_12 12.0-CURRENT FreeBSD 12.0-CURRENT #4 r320548: Sat Jul  1 
17:05:23 EDT 2017     root at FBSD_12:/usr/obj/usr/src/sys/MYKERNEL  amd64 
1200037 1200037

Vbox is broken after recent update to base system:

4 warnings generated.
kBuild: Linking VBox-xpcom-typelib
kBuild: Linking VBox-xpcom-string
kBuild: Linking VBox-xpcom-base
kBuild: Linking VBox-xpcom-ds
kBuild: Linking VBox-xpcom-io
kBuild: Linking VBox-xpcom-components
kBuild: Linking VBox-xpcom-threads
kBuild: Linking VBox-xpcom-xptinfo
kBuild: Linking VBox-xpcom-xptcall
kBuild: Linking VBox-xpcom-proxy
kBuild: Linking VBox-xpcom-ipcshared
kBuild: Linking VBoxXPCOMGlue_s
kBuild: Linking VBoxRT
kBuild: Compiling vboxwebsrv - 
/usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.22/src/VBox/Main/webservice/vboxweb.cpp
kBuild: Compiling vboxwebsrv - 
/usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.22/out/freebsd.amd64/release/obj/webservice/methodmaps.cpp
kBuild: Compiling vboxwebsrv - 
/usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.22/out/freebsd.amd64/release/obj/webservice/soapServer.cpp
kmk: *** 
[/usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.22/out/freebsd.amd64/release/obj/RuntimeBldProg/RuntimeBldProg.a] 
Segmentation fault (core dumped)
The failing command:
@/usr/local/bin/kmk_redirect -rti 
/usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.22/out/freebsd.amd64/release/obj/RuntimeBldProg/RuntimeBldProg.a.ar-script 
-- ar -M
kmk: *** 
[/usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.22/out/freebsd.amd64/release/obj/RuntimeBldProg/RuntimeBldProg.a] 
Deleting file 
`/usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.22/out/freebsd.amd64/release/obj/RuntimeBldProg/RuntimeBldProg.a.ar-script'
kmk: *** Waiting for unfinished jobs....
In file included from 
/usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.22/out/freebsd.amd64/release/obj/webservice/methodmaps.cpp:12:
/usr/ports/emulators/virtualbox-ose/work/VirtualBox-5.1.22/include/VBox/com/array.h:943:38: 
warning: binding dereferenced null
       pointer to reference has undefined behavior [-Wnull-dereference]
         AssertReturn(m.arr != NULL,  *((T *)NULL));
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~