cross-compilation support for python build

Lib/test/test_capi.py

 # Run the _testcapi module tests (tests for the Python/C API):  by defn,
 # these are all functions _testcapi exports whose name begins with 'test_'.
 
 from __future__ import with_statement
 import os
 import pickle
 import random
 import subprocess
 import sys
 import time
@@ skipping 171 matching lines @@
     def test(self):
         self.assertEqual(_testcapi.argparsing("Hello", "World"), 1)
 
 
 class EmbeddingTest(unittest.TestCase):
 
     @unittest.skipIf(
         sys.platform.startswith('win'),
         "test doesn't work under Windows")
     def test_subinterps(self):
-        # XXX only tested under Unix checkouts
-        basepath = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
+        # XXX only tested under Posix checkouts
+        basepath = support.SAVEDCWD
         oldcwd = os.getcwd()
         # This is needed otherwise we get a fatal error:
         # "Py_Initialize: Unable to get the locale encoding
         # LookupError: no codec search functions registered: can't find encoding"
         os.chdir(basepath)
         try:
-            exe = os.path.join(basepath, "Modules", "_testembed")
+            # XXX to be replaced by packaging.util
+            from distutils.spawn import find_executable
+            exe = find_executable("_testembed", basepath)
             if not os.path.exists(exe):
                 self.skipTest("%r doesn't exist" % exe)
             p = subprocess.Popen([exe],
                                  stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE)
             (out, err) = p.communicate()
             self.assertEqual(p.returncode, 0,
                              "bad returncode %d, stderr is %r" %
                              (p.returncode, err))
             if support.verbose:
@@ skipping 35 matching lines @@
     if threading:
         import time
         TestThreadState()
         t = threading.Thread(target=TestThreadState)
         t.start()
         t.join()
 
 
 if __name__ == "__main__":
     test_main()