Issue #13590: OS X Xcode 4 - improve support for universal extension modules
    In particular, fix extension module build failures when trying to use
    32-bit-only installer Pythons on systems with Xcode 4 (currently
    OS X 10.8, 10.7, and optionally 10.6).
    * Backport 3.3.0 fixes to 2.7 branch (for release in 2.7.4)
    * Since Xcode 4 removes ppc support, extension module builds now
      check for ppc compiler support and by default remove ppc and
      ppc64 archs when they are not available.
    * Extension module builds now revert to using system installed
      headers and libs (/usr and /System/Library) if the SDK used
      to build the interpreter is not installed or has moved.
    * Try to avoid building extension modules with deprecated
      and problematic Apple llvm-gcc compiler.  If original compiler
      is not available, use clang instead by default.
Issue #4844: ZipFile now raises BadZipfile when opens a ZIP file with an
incomplete "End of Central Directory" record.  Original patch by Guilherme
Polo and Alan McIntyre.
Issue #17049: Localized calendar methods now return unicode if a locale
includes an encoding and the result string contains month or weekday (was
regression from Python 2.6).
Issue #17041: Fix doctesting when Python is configured with the
--without-doc-strings.