libxml: Run bindgen during build
- Fixes https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1102187
- Fixes https://github.com/KWARC/rust-libxml/issues/73
- Forwarded upstream (with a minor change to avoid breaking the build on Windows) at https://github.com/KWARC/rust-libxml/pull/143
Edited by Antonin Delpeuch