The reflection failure is because the XML extension is used to check the
module dependency information, but that extension can be configured to
not depend on ext/libxml, resulting in a different output. The solution
is to check another extension instead.
The test failures in ext/xml/tests are because of different behaviour
between libxml2 and Expat error handling. These are expected differences
and the solution is to split the tests.
Closes GH-13522.
