CA-122205: Addressing build errors, also backing out blktap2 changes

The blktap2.py changes in commit 68286d16 are not relevant to this issue,
it could be worked on later.

Signed-off-by: Vineeth Thampi Raveendran <vineeth.thampi@citrix.com>
Acked-by: Thanos Makatos <thanos.makatos@citrix.com>

GitHub: closes #89 on xapi-project/sm