- Fix segfault with invalid coding.

- SF Bug #772896, unknown encoding results in MemoryError, which is not helpful

I will only backport the segfault fix.  I'll let Anthony decide if he wants
the other changes backported.  I will do the backport if asked.

Lib/test/test_coding.py

@@ -0,0 +1,21 @@
+
+import test.test_support, unittest
+import os
+
+class CodingTest(unittest.TestCase):
+    def test_bad_coding(self):
+        module_name = 'bad_coding'
+        self.assertRaises(SyntaxError, __import__, 'test.' + module_name)
+
+        path = os.path.dirname(__file__)
+        filename = os.path.join(path, module_name + '.py')
+        fp = open(filename)
+        text = fp.read()
+        fp.close()
+        self.assertRaises(SyntaxError, compile, text, filename, 'exec')
+
+def test_main():
+    test.test_support.run_unittest(CodingTest)
+
+if __name__ == "__main__":
+    test_main()