tests: Add libqemustub to qom-interface-check

The recent addition of util/error.c's dependency on error_report()
causes this test to fail to link due to a number of missing monitor
related symbols. All these symbols are however defined by libqemustub.
Add this libary to the link.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Revert "error: Don't use error_report() for assertion msgs."

This reverts commit d32934c84c72f57e78d430c22974677b7bcabe5d.

The original implementation before this patch makes abortive error
messages much more friendly. The underlying bug that required this
change is now fixed. Revert.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>