SAX tests failing under libxml2 v2.09.14

[dwarring]

Which is the current libxml2 version on Debian 12/13.

Looks as if SAX is completely broken. I also get the same errors if I build v2.09.14 locally. Latest libxml2 blead is OK, so this must have been a transient issue.

[dwarring]

More specifically, the StartElement and endElement callbacks seem to be ignored. startElementNS and endElementNS seem OK.

[dwarring]

The fix needs further work for compatibility with libxml2 v2.9.15+, which removes initxmlDefaultSAXHandler().

[dwarring]

I've restricted the fix to only work up to libxml2 v2.09.14. Hopefully the security patch wont be needed for libxml 2.10.0 on wards, which withdraws SAX1.

[dwarring]

Debian have just released a fixed version of libxml2. So this is a transient issue. Will back this fix out in a few weeks.