Determine CPU architecture & choose appropriate algorithm for BTRFS partitions

[py0xc3]

This is indirectly related to the bugzilla issue Hardware without AES-NI: use xchacha12/Adiantum instead of AES-XTS.

If the availability of AES-NI is checked to choose the most appropriate disk encryption (see the issue ticket), it might make sense to also check if the system is a 64 bit architecture.

If the system is a 64 bit architecture, the performance and consistency of BTRFS partitions can be improved by choosing xxhash instead of CRC32c by default for BTRFS. On one hand, xxhash is usually faster than CRC32c on 64 bit architectures (I expect most installations are already on 64 bit hardware). On the other hand, xxhash's 64 bit are much more resistant to collisions when compared to CRC32c's 32 bit.

Implementing the bugzilla ticket and the 64 bit-check together may save some work time, e.g. one function to get both information.