When running external programs such as a C compiler and getting an
error code, distutils only prints the program name.  With this change,
one can get the full command line by setting the DISTUTILS_DEBUG
environment variable.

This should have no compatibility issues, unless there are tools
that depend on the exact format of distutils debug messages.

Thanks to Amaury Forgeot d’Arc and Philip J. Eby.

Patch by Berker Peksag.

Patch by Berker Peksag.

Fix urllib.request.build_opener mocking in test_distutils (should fix some random buildbot failures)

Fix urllib.request.build_opener mocking in test_distutils (should fix some random buildbot failures)

already done by PyMODINIT_FUNC.

Change stacklevel in warnings.warn() for 'SO' key to 2.