`shutdown -p now` fails to power off with VirtualBox UEFI boot

[Yasuhiro KIMURA]

I have VirtualBox VM running 13-CURRENT. In order to switch from
legacy BIOS to UEFI I reinstalled OS by using
FreeBSD-13.0-CURRENT-amd64-20200611-r362037-disc1.iso. After that
`shutdow -p now` (or select 'ACPI shutdown' in VM menu) fails to power
off. Shutdown itself completes successfully. But power off never
happens and CPU usage keeps high until either closing or resetting VM.

I reinstalled OS by using
FreeBSD-13.0-CURRENT-amd64-20200618-r362292-disc1.iso but the problem
still happens. If I switch back to legacy BIOS then the problem
disappears. And it doesn't happen with either 11.4-RELEASE and
12.1-RELEASE.

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Yasuhiro KIMURA