VBox ugrade fails

[AN]

# date
Wed Apr 18 16:41:50 EDT 2012
[root at FBSD10 ~]# portsnap fetch update
Looking up portsnap.FreeBSD.org mirrors... 4 mirrors found.
Fetching snapshot tag from portsnap5.FreeBSD.org... done.
Latest snapshot on server matches what we already have.
No updates needed.
Ports tree is already up to date.

# uname -a
FreeBSD FBSD10 10.0-CURRENT FreeBSD 10.0-CURRENT #11 r234399: Tue Apr 17 
18:15:12 EDT 2012     root at FBSD10:/usr/obj/usr/src/sys/MYKERNEL  amd64

  portupgrade -va
--->  Session started at: Wed, 18 Apr 2012 16:42:42 -0400
--->  Upgrade of emulators/virtualbox-ose-kmod started at: Wed, 18 Apr 
2012 16:43:38 -0400
--->  Upgrading 'virtualbox-ose-kmod-4.1.8_1' to 
'virtualbox-ose-kmod-4.1.12' (emulators/virtualbox-ose-kmod)
--->  Build of emulators/virtualbox-ose-kmod started at: Wed, 18 Apr 2012 
16:43:38 -0400
--->  Building '/usr/ports/emulators/virtualbox-ose-kmod'

cd 
/usr/ports/emulators/virtualbox-ose-kmod/work/VirtualBox-4.1.12/out/freebsd.amd64/release/bin/src 
&& make SYSDIR=/usr/src/sys
*** Building 'vboxdrv' module ***
"/usr/share/mk/bsd.own.mk", line 483: MK_CLANG_IS_CC can't be set by a 
user.
*** [all] Error code 1

Stop in 
/usr/ports/emulators/virtualbox-ose-kmod/work/VirtualBox-4.1.12/out/freebsd.amd64/release/bin/src.
*** [do-build] Error code 1

Stop in /usr/ports/emulators/virtualbox-ose-kmod.
*** [build] Error code 1

Stop in /usr/ports/emulators/virtualbox-ose-kmod.
** Command failed [exit code 1]: /usr/bin/script -qa 
/tmp/portupgrade20120418-95793-1hmpppe-0 env UPGRADE_TOOL=portupgrade 
UPGRADE_PORT=virtualbox-ose-kmod-4.1.8_1 UPGRADE_PORT_VER=4.1.8_1 make
** Fix the problem and try again.
--->  Build of emulators/virtualbox-ose-kmod ended at: Wed, 18 Apr 2012 
16:43:59 -0400 (consumed 00:00:21)
--->  Upgrade of emulators/virtualbox-ose-kmod ended at: Wed, 18 Apr 2012 
16:43:59 -0400 (consumed 00:00:21)
--->  ** Upgrade tasks 2: 0 done, 1 ignored, 0 skipped and 1 failed


It seems there is a problem with VirtualBox and the file 
/usr/share/mk/bsd.own.mk on current.  I am _not_ using Clang, just the 
standard base compiler.

# cat /etc/make.conf
OVERRIDE_LINUX_BASE_PORT=f10
QT4_OPTIONS= QGTKSTYLE
WITH_OPENSSL_PORT=yes
# added by use.perl 2012-04-04 01:11:13
PERL_VERSION=5.14.2
MALLOC_PRODUCTION=yes