Fix renamed modules

A few parts of the standard library were renamed in Python 3.  Import
the correct name depending on whether we're running inside Python 2 or 3.

Author: alexwlchan

utils/SwiftBuildSupport.py

@@ -12,12 +12,16 @@
 
 from __future__ import print_function
 
-import ConfigParser
 import os
 import pipes
 import subprocess
 import sys
 
+if sys.version_info < (3, 0):
+    import ConfigParser
+else:
+    import configparser as ConfigParser
+
 
 HOME = os.environ.get("HOME", "/")
 

utils/gyb.py

@@ -5,12 +5,17 @@
 from __future__ import print_function
 
 import re
-from cStringIO import StringIO
 import tokenize
 import textwrap
 from bisect import bisect
 import os
 
+import sys
+if sys.version_info < (3, 0):
+    from cStringIO import StringIO
+else:
+    from io import StringIO
+
 def getLineStarts(s):
     """Return a list containing the start index of each line in s.