resize/test-virt-resize.pl: Enable virt-resize debugging

When the test fails it's very useful to be able to see the internal
calculations used by virt-resize.

Author: rwmjones

resize/test-virt-resize.pl

@@ -311,6 +311,7 @@
 # Create the virt-resize command.
 my @command = (
     "virt-resize",
+    "--debug",
     "--format", $source_format,
     "--output-format", $target_format,
     );