Re: [Libvir] PATCH: Make test suite debug mode more friendly

When the test suites fail, we have a DEBUG_TESTS=1 environment variable which can be set to show the full XML doc or string pair that failed to match. Unfortunately these docs can be quite large, so it is hard to spot the difference between the actual and expected output. So this patch introduces a virtTestDifference(actual, expect) method which will trim the head & tail of the actual & expected strings until the point at which they differ. This gives immediate clear feedback on where the bug is Second, it will enumerate each test condition & pretty print align things a little better.