[xml] xml2-config incorrectly passes private dependencies when linking dynamically

[Hugh McMaster <hugh mcmaster outlook com>]

`xml2-config --libs` prints private library dependencies by default. This is un-necessary and incorrect when linking against libxml2 dynamically.

Debian patches libxml and libxslt to allow `--libs --static`, but as pointed out in [1], this breaks existing applications expecting all libraries, including private dependencies.

The recommendation in [2] is to patch xml2-config to add a --dynamic option to --libs, before patching libxslt to fix several issues with private dependencies.

I’ve submitted a patch for xml2-config in a pull request on Gitlab [3].

Thank you,

Hugh

[1] https://mail.gnome.org/archives/xslt/2019-June/msg00005.html

[2] https://mail.gnome.org/archives/xslt/2019-June/msg00008.html

[3] https://gitlab.gnome.org/GNOME/libxml2/merge_requests/23