Add import_function method to test.test_support, and modify a number of

tests that expect to be skipped if imports fail or functions don't
exist to use import_function and import_module.  The ultimate goal is
to change regrtest to not skip automatically on ImportError.  Checking
in now to make sure the buldbots don't show any errors on platforms
I can't direct test on.

Lib/test/test_startfile.py

@@ -9,9 +9,11 @@
 
 import unittest
 from test import test_support
+import os
+from os import path
+
+startfile = test_support.import_function(os, 'startfile')
 
-# use this form so that the test is skipped when startfile is not available:
-from os import startfile, path
 
 class TestCase(unittest.TestCase):
     def test_nonexisting(self):