libblkid: zfs: fix unaligned memory access on SPARC

libblkid: zfs: fix unaligned memory access on SPARC

SPARC requires aligned memory access for uint32_t values. The ZFS code
was directly dereferencing uint32_t pointers that could be unaligned due
to XDR encoding, causing SIGBUS crashes. Introduce copy_be32_to_cpu()
helper using memcpy to safely read from potentially unaligned memory.

Addresses: https://github.com/util-linux/util-linux/issues/4010

Signed-off-by: Ameer Hamza <ahamza@ixsystems.com>