sysutils/grub2-bhyve: Add support for additional EXT4 incompatible features

[oshogbo]

Summary

Handle the following EXT4 incompatible features:

EXT4_FEATURE_INCOMPAT_MMP (Multi-Mount Protection)
Prevents multiple read-write mounts of the same filesystem.
Since grub2-bhyve mounts filesystems read-only, it is safe to ignore.

EXT4_FEATURE_INCOMPAT_CSUM_SEED
Allows tools such as tune2fs to change the UUID on a mounted
metadata-checksummed filesystem. Safe to ignore because the
driver does not perform checksum verification.

EXT4_FEATURE_INCOMPAT_LARGEDIR
Enables directories larger than 2GB and 3-level htrees.
Safe to ignore because the GRUB ext2 driver does not implement
DIR_INDEX.

This patch mirrors upstream behavior. It unblocks booting from
distributions such as Alpine Linux.

[lwhsu]

See also: https://bugs.freebsd.org/286702

[oshogbo]

@lwhsu Do you want me to close this review?

[lwhsu]

The only thing we need more is bump the PORTREVISION.

[lwhsu]

@oshogbo I think you can commit this, as you're earlier than the patch is created to https://bugs.freebsd.org/286702 , btw, the current policy is that the cross-repo commit is encouraged and no really need explicitly approval. Of course, asking review is still encouraged, just like in any repository.