This ticket fixes what was broken by #29025.

Previous related tickets:

• make numpy and scipy use pkg-config to find blas/lapack #20157: make numpy and scipy use pkg-config to find blas/lapack
• Scipy fails to build with ATLAS #22047: Scipy fails to build with ATLAS
• numpy: site.cfg needs a [DEFAULT] section #29025: numpy: site.cfg needs a [DEFAULT] section

References:

scipy/setup.py at master · scipy/scipy
https://github.com/scipy/scipy/blob/master/scipy/setup.py

numpy/system_info.py at master · numpy/numpy
https://github.com/numpy/numpy/blob/master/numpy/distutils/system_info.py

python - How to check BLAS/LAPACK linkage in NumPy and SciPy? - Stack Overflow
https://stackoverflow.com/questions/9000164/how-to-check-blas-lapack-linkage-in-numpy-and-scipy

CC: @kiwifb @dimpase @mwageringel @vbraun

Component: packages: standard

Author: Dima Pasechnik

Branch/Commit: dba7aef

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/29051