fixed the way the cfg file markers values are split under win32
diff --git a/Lib/packaging/config.py b/Lib/packaging/config.py
index 6bbfdc3..6df2bab 100644
--- a/Lib/packaging/config.py
+++ b/Lib/packaging/config.py
@@ -21,7 +21,8 @@
     if not vals_str:
         return
     fields = []
-    for field in vals_str.split(os.linesep):
+    # the line separator is \n for setup.cfg files
+    for field in vals_str.split('\n'):
         tmp_vals = field.split('--')
         if len(tmp_vals) == 2 and not interpret(tmp_vals[1]):
             continue