Patch by Ralf Schmitt.

- Actually check the contents of the file created by bdist_dumb.
- Don’t use “RECORD” as filename for non-PEP 376 record file
- Don’t start method name with “_test”, it looks like a disabled test
  method instead of an helper method
- Fix some idioms (assertIn, addCleanup)

Bug reported by Hartmut Goebel and patch contributed by Carl Robben.
Untested backport of the fix committed and tested for 3.2.

These regex changes fix a number of issues for distutils on Windows:
- #6884: impossible to include a file starting with 'build'
- #9691 and #14004: sdist includes too many files
- #13193: test_filelist failures

This commit replaces the incorrect changes done in 557a973709de,
c566a3447ba1 and 3925081a7ca0 to fix #13193; we were too eager to fix
the test failures and I did not study the code enough before
greenlighting patches.  This time we have unit tests from the problems
reported by users to be sure we have the right fix.

Thanks to Nadeem Vawda for his help.

The code used to call os.path.join to build a regex but without escaping
the backslash, which lead to test failures on Windows.  Antoine Pitrou
fixed it in 557a973709de by enhancing the code to accept both / and \,
with proper escaping, but in my opinion this goes against the distutils
feature freeze, hence this change.

has left two versions of customize_compiler, the original in
distutils.sysconfig and another copy in distutils.ccompiler, with some
parts of distutils calling one and others using the other.
Complete the revert back to only having one in distutils.sysconfig as
is the case in 3.x.

Distutils-based packages with C extension modules may fail because
Apple has removed gcc-4.2, the version used to build python.org
64-bit/32-bit Pythons.  If the user does not explicitly override
the default C compiler by setting the CC environment variable,
Distutils will now attempt to compile extension modules with clang
if gcc-4.2 is required but not found. Also as a convenience, if
the user does explicitly set CC, substitute its value as the default
compiler in the Distutils LDSHARED configuration variable for OS X.
(Note, the python.org 32-bit-only Pythons use gcc-4.0 and the 10.4u
SDK, neither of which are available in Xcode 4.  This change does not
attempt to override settings to support their use with Xcode 4.)

Emergency fix for #13803 bootstrap issue: Under Solaris, distutils doesn't include bitness in the directory name

Issue #11638: Adding test to ensure .tar.gz files can be generated by sdist command with unicode metadata, based on David Barnett's patch.
Issue #11638: Added tests to capture failures in make_tarball with various unicode strings.
Following fix for Issue #13639, these tests now pass.

"recursive-include" directive now recognizes both legal path separators.

Patch by Justin Love.

The check command was fixed by Kirill Kuzminykh.

The register command was using StringIO.getvalue, which uses “''.join”
and thus coerces to str using the default encoding (ASCII), so I changed
the code to use one extra intermediary list and correctly encode to
UTF-8.

Patch by Hallvard B Furuseth.

I have tests to add in this file and it’s always nice to start from a
clean base.  I’ve also changed a test that used to write an invalid
config file ('[global]command_packages = etc.' on one line), but the
test passes before and after this change, so either it magically works
or the test is poorly written.  Sigh.

sdist used to crash with a full traceback dump instead of printing a
nice warning with the faulty line number.

I need to copy the xxmodule.c file in other tests, so I moved the
support code to distutils.tests.support and improved it:
- don’t skip when run from the Lib/distutils/tests directory
- use proper skip machinery instead of custom print/return/test suite
  fiddling.

I also took out the fixup_build_ext function, which is needed for tests
to pass on Unix shared builds and Windows debug builds.

Finally, I cleaned up a few things:
- don’t remove directories in tearDown when the parent class’ tearDown
  has already registered the directories for removal
- simplify restoration of sys.path
- remove a few unused names found by pyflakes.