Missing dependencies on Buster for Virtualbox 6.1.6

Looks pretty dire for now.

The following packages have unmet dependencies:|
libc6-dev : Breaks: libgcc-8-dev (< 8.4.0-2~) but 8.3.0-6 is to be installed

I’ve worked around 1 issue.

https://gitlab.com/whonix/Whonix/-/commit/8025c190e78ad1eeeb9a6e1eca5b908519832354

But now another issue similar to build failing on Debian buster at kmk_builtin_append out/obj/VBoxGlobal/qtrcc/VirtualBox2_x4.gen.cpp (which could be solved by not building inside Qubes but building on real Debian).

Now with VirtualBox 6.1.6 build failing even on Debian.

c/runtime/UISession.o.dep" “” “/home/user/whonix_binary/temp_packages_virtualbox/virtualbox-6.1.8-dfsg/src/VBox/Frontends/VirtualBox/src/runtime/UISession.cpp:” “”
kmk: *** Exiting with status 2

Hence asking for help:
https://twitter.com/Whonix/status/1268525273852661765