stdenv-darwin: upgrade a few more things

It's a long build and generally painful to split into smaller commits,
so I apologize for lumping many changes into one commit but this is far
easier.

There are still several outdated parts of the darwin stdenv but these
changes should bring us closer to the goal.

Fixes #18461

pkgs/development/interpreters/python/cpython/2.7/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, self, callPackage, python27Packages
+{ stdenv, fetchurl, fetchpatch, self, callPackage, python27Packages
 , bzip2, openssl, gettext
 
 , includeModules ? false
@@ -44,6 +44,14 @@ let
       ./deterministic-build.patch
 
       ./properly-detect-curses.patch
+
+      # FIXME: get rid of this after the next release, when the commit referenced here makes
+      # it in. We need it until then because it breaks compilation of programs that use
+      # locale with clang 3.8 and higher.
+      (fetchpatch {
+        url    = "https://hg.python.org/cpython/raw-rev/e0ec3471cb09";
+        sha256 = "1jdgb70jw942r4kmr01qll7mk1di8jx0qiabmp20jhnmha246ivq";
+      })
     ] ++ optionals stdenv.isLinux [
 
       # Disable the use of ldconfig in ctypes.util.find_library (since