PIP3 compile not working on Catalina
I found out that this would work:
pip3 install --global-option=build_ext  --global-option=&quot;-I`xcrun --show-sdk-path`/usr/include/libxml2&quot; ovirt-engine-sdk-python

This specifically adds the path to libxml2 to the include path. How to solve this in a more general way I do not know however.