Fix for issue #9164: with this patch sysconfig and distuls don't break

when duplicate '-arch foo' flags end up in CFLAGS (which may happen when
building a universal build using macports)

Lib/distutils/util.py

@@ -144,8 +144,7 @@ def get_platform ():
                 cflags = get_config_vars().get('CFLAGS')
 
                 archs = re.findall('-arch\s+(\S+)', cflags)
-                archs.sort()
-                archs = tuple(archs)
+                archs = tuple(sorted(set(archs)))
 
                 if len(archs) == 1:
                     machine = archs[0]