migration: Create populate_compress()

So we don't have to access compression_counters from outside
ram-compress.c.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Lukas Straub <lukasstraub2@web.de>
Message-ID: <20230613145757.10131-7-quintela@redhat.com>
3 files changed