Remove libpython output

[h-vetinari]

libpython is becoming a real output for the python recipe itself (conda-forge/python-feedstock#894). We need to remove the output here, change all (non-archived) consuming recipes, and then likely repodata-patch existing builds to point to distutils-activate-mingw instead, and mark the old builds as broken.

This search finds 16 non-archived feedstocks that use this:

• MNT: replace use of libpython anuga-feedstock#24
• MNT: replace use of libpython awex-feedstock#17
• MNT: replace use of libpython capytaine-feedstock#53
• MNT: replace use of libpython eatpy-feedstock#13
• MNT: replace use of libpython finesse-feedstock#77
• MNT: replace use of libpython framel-feedstock#51
• MNT: replace use of libpython gala-feedstock#42
• MNT: replace use of libpython gdcm-feedstock#69
• MNT: replace use of libpython nds2-client-swig-feedstock#45
• MNT: replace use of libpython pygetm-feedstock#39
• MNT: replace use of libpython pygotm-feedstock#20
• MNT: replace use of libpython pyhams-feedstock#35
• MNT: replace use of libpython pyreadr-feedstock#61
• MNT: replace use of libpython python-quickjs-feedstock#13
• MNT: replace use of libpython rvlib-feedstock#31
• MNT: replace use of libpython wisdem-feedstock#109