libqos/ahci: Add ahci_clean_mem

Clean up guest memory being used in ahci_clean_mem, to be
called during ahci_shutdown. With all guest memory leaks removed,
add an option to the allocator to throw an assertion if a leak
occurs.

This test adds some sanity to both the AHCI library and the
allocator.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1423158090-25580-18-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
