Report error and exit upon compiling error, otherwise the iotests output
will be pure noise.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20170926110134.2786-1-famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>