MacOSX: detect the architectures supported by

Tk.framework and build _tkinter only for those
architectures.

This replaces the hardcoded solution that is no
longer valid now that 64-bit capable versions of
Tk are available on OSX.

setup.py

@@ -1499,17 +1499,15 @@ class PyBuildExt(build_ext):
         # architectures.
         cflags = sysconfig.get_config_vars('CFLAGS')[0]
         archs = re.findall('-arch\s+(\w+)', cflags)
-        if 'x86_64' in archs or 'ppc64' in archs:
-            try:
-                archs.remove('x86_64')
-            except ValueError:
-                pass
-            try:
-                archs.remove('ppc64')
-            except ValueError:
-                pass
+        fp = os.popen("file %s/Tk.framework/Tk | grep 'for architecture'"%(F,))
+        detected_archs = []
+        for ln in fp:
+            a = ln.split()[-1]
+            if a in archs:
+                detected_archs.append(ln.split()[-1])
+        fp.close()
 
-            for a in archs:
+        for a in detected_archs:
             frameworks.append('-arch')
             frameworks.append(a)