Virtualbox update to 6.1.20.

[madpilot]

Summary

I have prepared this update to VirtualBox 6.1.20.

It build in poudriere with default options and runs on my system for light loads.

I plan to commit this once I'm done testing, I'm posting it here so others can take a look too.

This patch does not include the changes I sent in bugzilla bug 255208 trying to fix the additions vboxvfs module kernel panic inside jails.

I plan to commit that before proceeding with the update.

Test Plan

Run more poudriere tests with non defualt option.

Stress test more at runtime.

[madpilot]

Noticed port still has some #if __FreeBSD_version referencing old unsupported versions.

I updated the patch to remove those to simplify patches.

Please note I'm intentionally not removing the ones in upstream code, patches are already complex enough, just removing the ones we used to add and don't need anymore.

[madpilot]

Committed in ports d2441db781c7

Sorry I forgot to mention the revision in the commit message.