There have been no users of the xc_compression_*() interface since Migration
v2 replaced legacy migration (2015, c/s b15bc4345).
It would need adjusting to fit into migration v2, and can be pulled out of git
history if someone wants to resurrect it in the future.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>