Fix: support VPATH build for tests

Fixes #613

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: don't report error if UST app dies

An application dying unexpectedly is a normal behavior so the execution
must continue and not report an error when sending commands onto the
dying application.

Signed-off-by: David Goulet <dgoulet@efficios.com>