Fix GH-11160: Few tests failed building with new libxml 2.11.0

[nielsdos]

It's possible to categorise the failures into 2 categories:

• Changed error message. In this case we either duplicate the test and modify the error message. Or if the change in error message is small, we use the EXPECTF matchers to make the test compatible with both old and new versions of libxml2.
• Missing warnings. This is caused by a change in libxml2 where the parser started using SAX APIs internally [1]. In this case the error_type passed to php_libxml_internal_error_handler() changed from PHP_LIBXML_ERROR to PHP_LIBXML_CTX_WARNING because it internally started to use the SAX handlers instead of the generic handlers. However, for the SAX handlers the current input stack is empty, so nothing is actually printed. I fixed this by falling back to a regular warning without a filename & line number reference, which mimicks the old behaviour. Furthermore, this change now also shows an additional warning in a test which was previously hidden.

[1] https://gitlab.gnome.org/GNOME/libxml2/-/commit/9a82b94a94bd310db426edd453b0f38c6c8f69f5

[andypost]

Thank you! it fixes all tests on 7 arches

[andypost]

btw using patch with PHP-8.0

BORKED TEST SUMMARY
---------------------------------------------------------------------
duplicated SKIPIF section [/builds/alpine/aports/testing/php8/src/php-8.0.28/ext/dom/tests/DOMDocument_loadXML_error2_pre2_11.phpt]
duplicated SKIPIF section [/builds/alpine/aports/testing/php8/src/php-8.0.28/ext/dom/tests/DOMDocument_load_error2_pre2_11.phpt]

[nielsdos]

btw using patch with PHP-8.0

BORKED TEST SUMMARY
---------------------------------------------------------------------
duplicated SKIPIF section [/builds/alpine/aports/testing/php8/src/php-8.0.28/ext/dom/tests/DOMDocument_loadXML_error2_pre2_11.phpt]
duplicated SKIPIF section [/builds/alpine/aports/testing/php8/src/php-8.0.28/ext/dom/tests/DOMDocument_load_error2_pre2_11.phpt]

In 8.0 the way to check for extension availability was different than in 8.1+. This means that on 8.0 the tests already have a SKIPIF section, which is what the test runner complains about. If you want to fix it on 8.0 then you need to place the if-check I added below the <?php include('skipif.inc'); ?> line.

[andypost]

Used your suggestion and now both pass https://gitlab.alpinelinux.org/alpine/aports/-/pipelines/162300