btrfs: test send issue with non-aligned clone operations

btrfs: test send issue with non-aligned clone operations

Test for an issue in btrfs send where it sent clone operations to user
space with a range (offset + length) that was not aligned with the block
size. This caused the btrfs receive command to send such clone operations
to the ioctl clone API, which would return -EINVAL errors to btrfs receive,
causing the receive command to abort immediately.

This corresponding btrfs linux kernel patch that fixes this issue is at:

https://patchwork.kernel.org/patch/3470401/

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>