While emulators/virtualbox-ose has a patch that was updated for using vm_page_reclaim_contig instead of vm_pageout_grow_cache when __FreeBSD_version >= 1100092, emulators/virtualbox-ose-additions does not.
pkg install virtualbox-ose-additions results in a vboxguest.ko that will not load for __FreeBSD_version >= 1100092 because of the old vm_pageout_grow_cache reference.
Attempting to portmaster emulators/virtualbox-ose-additions results in:
. . ./VirtualBox-4.3.34/src/VBox/Runtime/r0drv/freebsd/memobj-r0drv-freebsd.c:231:9: error:
implicit declaration of function 'vm_pageout_grow_cache' is invalid in C99
vm_pageout_grow_cache(cTries, 0, VmPhysAddrHigh);
which stops the build. This is from there being no patch for emulators/virtualbox-ose-additions's memobj-r0drv-freebsd.c source.
I found no UPDATING material about the issues (11.0-CURRENT or ports).
Apparently when emulators/virtualbox-ose is updated that is sufficient context for virtualbox-ose-additions to also be updated. (I came up without another reason to update my ports vintage via svnlite. Afterwards emulators/virtualbox-ose-additions built fine.)
In other words: my originally looking up to see if emulators/virtualbox-ose-additions had an update was inappropriate because of an indirection to another port that I was not explicitly building or directly interested in.
I still would suggest UPDATING notes for either or both of ports and 11.0-CURRENT relative to virtualbox, including virtualbox-ose-additions.