suspend_vchan: update for vchan.0.9.2

The vchan API only exposes blocking now.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
block_perf: add a watchdog thread

Detect deadlocks and print an error. Periodically dump the state
of each event channel.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Merge pull request #13 from djs55/fix-vchan

suspend_vchan: update for vchan.0.9.2