Replace filter() calls with list comprehensions

In Python 3, filter() returns an iterator.
Use list comprehensions instead.

Reviewed-By: Christian Heimes <cheimes@redhat.com>
Reviewed-By: Jan Cholasta <jcholast@redhat.com>

ipaplatform/setup.py.in

@@ -63,7 +63,7 @@ def setup_package():
             description = DOCLINES[0],
             long_description = "\n".join(DOCLINES[2:]),
             download_url = "http://www.freeipa.org/page/Downloads",
-            classifiers=filter(None, CLASSIFIERS.split('\n')),
+            classifiers=[line for line in CLASSIFIERS.split('\n') if line],
             package_dir = {'ipaplatform': ''},
             packages = ["ipaplatform",
                         "ipaplatform.base",