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

Issue #19544 and Issue #6286: Restore use of urllib over http allowing use of http_proxy for Distutils upload command, a feature accidentally lost in the rollback of distutils2.

Issue 19544 and Issue #7457: Restore the read_pkg_file method to distutils.dist.DistributionMetadata accidentally removed in the undo of distutils2.

Issue #19286: Adding test demonstrating the failure when a directory is found in the package_data globs.

Patch by Oscar Benjamin.

The only file change is adding the v3.2.5 tag to 3.3's .hgtags file.

is overriden with the CC environment variable, use the new compiler as
the default for linking if LDSHARED is not also overriden.  This restores
Distutils behavior introduced in 3.2.3 and inadvertently dropped in 3.3.0.

distutils.cfg when a venv is active.

  when imported, instead doing it at build time.  This makes importing
  sysconfig faster and reduces Python startup time by 20%.

  two makefile macros SHLIB_SUFFIX and EXT_SUFFIX. SO now has the value of
  SHLIB_SUFFIX again (as in 2.x and 3.1). The SO macro is removed in 3.4.

  two makefile macros SHLIB_SUFFIX and EXT_SUFFIX. SO now has the value of
  SHLIB_SUFFIX again (as in 2.x and 3.1). The SO macro is removed in 3.4.