Build issues

[DougBurke]

The build "works for me"™ but that's not ideal.

Sherpa has a setup.cfg with a [xspec_config] section used to configure the build - e.g. define the include and library locaitons and names of the libraries - but how do we do this in the new PEP 517 and PEP 518 world?

For example, https://packaging.python.org/guides/packaging-binary-extensions/ is (at the time) marked as last reviewed in 2013, well before PEP 517/518.