iotests: Split 214 off of 122

iotests: Split 214 off of 122

Commit abd3622cc03cf41ed542126a540385f30a4c0175 added a case to 122
regarding how the qcow2 driver handles an incorrect compressed data
length value.  This does not really fit into 122, as that file is
supposed to contain qemu-img convert test cases, which this case is not.
So this patch splits it off into its own file; maybe we will even get
more qcow2-only compression tests in the future.

Also, that test case does not work with refcount_bits=1, so mark that
option as unsupported.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180406164108.26118-1-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>