2.10 changes ABI without warning

It seems like a lot of change and cleanup and removals have gone into libxml 2.10. We noticed downstream that, built with the same options as 2.9.14, 111 symbols were removed from libxml2.so.2 without the soname changing. This broke quite a lot of dependent applications.

This doesn't seem like appropriate library maintenance? Symbols should not disappear without an soname change like this.

We figured out that building with --with-legacy --with-ftp --with-xptr-locs should probably bring back the important ones, leaving only the removals from 4a8c71eb and fe9f76eb , which probably shouldn't cause problems in practice. But still, it kinda feels like an soname bump should have happened here.