btrfs: add test for btrfs cloning with file holes

btrfs: add test for btrfs cloning with file holes

Regression test for the btrfs ioctl clone operation when the source range
contains hole(s) and the FS has the NO_HOLES feature enabled (file holes
don't need file extent items in the btree to represent them).

This issue is fixed by the following linux kernel btrfs patch:

    Btrfs: fix clone to deal with holes when NO_HOLES feature is enabled

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>