Allow specified modules to be compiled without optimization

[eirikurj]

Purpose

This PR proposes a way to compile specified modules without optimization to be able to use optimization flags such as -ffast-math without altering the behavior for checking NaN behavior.

Expected time until merged

As long as necessary

Type of change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe)

Testing

Please check that the modules are built in correct order and without optimization, both for real and complex.

Checklist

• I have run flake8 and black to make sure the Python code adheres to PEP-8 and is consistently formatted
• I have formatted the Fortran code with fprettify or C/C++ code with clang-format as applicable
• I have run unit and regression tests which pass locally with my changes
• I have added new tests that prove my fix is effective or that my feature works
• I have added necessary documentation

[sseraj]

I had to make some changes to get the real build working. The complex build does not work though. I think we have to update src_cs/build/Makefile

[eirikurj]

Ah yes, let me address this.

[eirikurj]

@sseraj, pushed some fixes. I also updated the description with "testing" description, just to make sure its there.

[sseraj]

I confirmed that this catches NaNs for my complex case