Hardcoding ARCHFLAGS breaks the build against fink's python

Fink's python is either i386 or amd64, but not universal. Setting ARCHFLAGS to the
empty string produces a successful build against both OS X python and fink python.
The modules will no longer be universal -- if that is an issue, we can change the
test to extract ARCHFLAGS from distutils.sysconfig and remove ppc if necessary.

setup.py

@@ -386,7 +386,7 b" if sys.platform == 'darwin' and os.path."
     # Also parse only first digit, because 3.2.1 can't be parsed nicely
     if (version.startswith('Xcode') and
         StrictVersion(version.split()[1]) >= StrictVersion('4.0')):
-        os.environ['ARCHFLAGS'] = '-arch i386 -arch x86_64'
+        os.environ['ARCHFLAGS'] = ''
 
 setup(name='mercurial',
       version=setupversion,