CP-7396: Ensure tapdisk reports metrics to rrdd.

- Register tapdisk with rrdd as a plugin when we open a new tapdisk.
- Deregister tapdisk with rrdd before we detach the tapdisk.

Signed-off-by: Siddharth Vinothkumar <siddharth.vinothkumar@citrix.com>
Reviewed-by: Vineeth Thampi Raveendran <vineeth.thampi@citrix.com>

GitHub: closes #75 on xapi-project/sm
CA-125230: Fix compilation for 64 bit

Support pack use fixed build architecture.
Change to detect architecture to fix building on 64 bit architecture and
stay compatible with 32 bit one.

Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Acked-by: Germano Percossi <germano.percossi@citrix.com>

GitHub: closes #68 on xapi-project/sm
CA-117628: allow LVM metadata updates when running through plug-in

This patch uses the LVM configuration file that allows metadata updates when
running LVM commands on the master through the plug-in. In addition,
this patch introduces checks on the return value of a few functions.

Signed-off-by: Thanos Makatos <thanos.makatos@citrix.com>
Acked-by: Germano Percossi <germano.percossi@citrix.com>

GitHub: closes #70 on xapi-project/sm