setup.py: don't call splitlines twice on the output of xcodebuild (issue3277)

setup.py

@@ -454,7 +454,7 b" if sys.platform == 'darwin' and os.path."
     # distutils.sysconfig
     version = runcmd(['/usr/bin/xcodebuild', '-version'], {})[0].splitlines()
     if version:
-        version = version.splitlines()[0]
+        version = version[0]
         xcode4 = (version.startswith('Xcode') and
                   StrictVersion(version.split()[1]) >= StrictVersion('4.0'))
     else: