Support partition and raw drive encryption/mounting on OpenBSD (low priority)

[justanotherscript]

On OpenBSD, the "Encrypt a non-system partition/drive" option is available in the GUI, but it does not work.

After entering the doas/sudo password, VeraCrypt immediately displays:

"Not enough data available."

VeraCrypt containers already work well on OpenBSD, so the remaining missing functionality is support for encrypting non-system partitions and drives, similar to the implementation available on FreeBSD.