Enable cross compilation for cpython 2.7 (#50245)

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

@@ -104,6 +104,8 @@ let
       # only works for GCC and Apple Clang. This makes distutils to call C++
       # compiler when needed.
       ./python-2.7-distutils-C++.patch
+    ] ++ optional (stdenv.hostPlatform != stdenv.buildPlatform) [
+      ./cross-compile.patch
     ];
 
   preConfigure = ''
@@ -176,10 +178,14 @@ let
     LIBRARY_PATH = makeLibraryPath paths;
   };
 
+  # Python 2.7 needs this
+  crossCompileEnv = stdenv.lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform)
+                      { _PYTHON_HOST_PLATFORM = stdenv.hostPlatform.config; };
+
   # Build the basic Python interpreter without modules that have
   # external dependencies.
 
-in stdenv.mkDerivation {
+in stdenv.mkDerivation ({
     name = "python-${version}";
     pythonVersion = majorVersion;
 
@@ -278,4 +284,4 @@ in stdenv.mkDerivation {
       # in case both 2 and 3 are installed.
       priority = -100;
     };
-  }
+  } // crossCompileEnv)