cmake >= 2.8.12 doesn't generate .pdb files for static libs,
and points out that they aren't useful anyway:

  http://public.kitware.com/Bug/view.php?id=14600

remove .pdb handling for static libs regardless of cmake version


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1625175 13f79535-47bb-0310-9956-ffa450edef68