Replace backticks with repr() or "%r"

From SF patch #852334.
diff --git a/Tools/freeze/winmakemakefile.py b/Tools/freeze/winmakemakefile.py
index 763e820..8570f3d 100644
--- a/Tools/freeze/winmakemakefile.py
+++ b/Tools/freeze/winmakemakefile.py
@@ -51,7 +51,7 @@
         sys.stdout = save
 
 def realwork(vars, moddefns, target):
-    version_suffix = `sys.version_info[0]`+`sys.version_info[1]`
+    version_suffix = "%r%r" % sys.version_info[:2]
     print "# Makefile for Microsoft Visual C++ generated by freeze.py script"
     print
     print 'target = %s' % target