* MAINT: use list-based APIs to call subprocesses
* TST, MAINT: add a test for mingw32ccompiler.build_import, clean up lib2def
Co-authored-by: Matti Picus <matti.picus@gmail.com>
Co-authored-by: Eric Wieser <wieser.eric@gmail.com>

* Cleanup unused imports (F401) of mostly standard Python modules,
  or some internal but unlikely referenced modules
* Where internal imports are potentially used, mark with noqa
* Avoid redefinition of imports (F811)

As numpy is Python 3 only, these import statements are now unnecessary
and don't alter runtime behavior.

This makes it easier to visually jump between functions.

A couple places have changed to not emit leading whitespace where they previously did. Since this is C code and not fortran, that doesn't matter.

Both of these functions are better exposed through `distutils.ccompiler`, but neither are used anyway