[2.7] Backport macOS universal build and installer fixes from 3.6. (GH-6469)

These include:

- bpo-32726: Provide an additional, more modern macOS installer variant that
  supports macOS 10.9+ systems in 64-bit mode only. Upgrade the supplied
  third-party libraries to OpenSSL 1.0.2n and SQLite 3.22.0. The 10.9+
  installer now supplies its own private copy of Tcl/Tk 8.6.8.

- bpo-24414: Default macOS deployment target is now set by ``configure`` to
  the build system's OS version (as is done by Python 3), not ``10.4``;
  override with, for example, ``./configure MACOSX_DEPLOYMENT_TARGET=10.4``.

- bpo-19019: All 2.7 macOS installer variants now supply their own version
  of ``OpenSSL 1.0.2``; the Apple-supplied SSL libraries and root
  certificates are not longer used.  The ``Installer Certificate`` command
  in ``/Applications/Python 2.7`` may be used to download and install a
  default set of root certificates from the third-party ``certifi`` package.

- bpo-11485: python.org macOS Pythons no longer supply a default SDK value
  (e.g. ``-isysroot /``) or specific compiler version default (e.g.
  ``gcc-4.2``) when building extension modules.  Use ``CC``, ``SDKROOT``,
  and ``DEVELOPER_DIR`` environment variables to override compilers or to
  use an SDK.  See Apple's ``xcrun`` man page for more info.

- prepare for pending Apple removal of 32-bit support in future macOS release

1 files changed, 1 insertions, 0 deletions

diff --git a/Mac/BuildScript/scripts/postflight.documentation b/Mac/BuildScript/scripts/postflight.documentation
index b9f28a5152..3cbbc1bf10 100755
--- a/Mac/BuildScript/scripts/postflight.documentation
+++ b/Mac/BuildScript/scripts/postflight.documentation
@@ -12,6 +12,7 @@ SHARE_DOCDIR_TO_FWK="../../.."
 # make link in /Applications/Python m.n/ for Finder users
 if [ -d "${APPDIR}" ]; then
     ln -fhs "${FWK_DOCDIR}/index.html" "${APPDIR}/Python Documentation.html"
+    open "${APPDIR}" || true  # open the applications folder
 fi
 
 # make share/doc link in framework for command line users