bpo-12915: Skip test_pkgutil.test_name_resolution() non-encodable filenames (GH-18720)

When filesystem encoding cannot encode the Unicode string used for a filename
continue testing with the next example.
diff --git a/Lib/test/test_pkgutil.py b/Lib/test/test_pkgutil.py
index 53456c2..b162f99 100644
--- a/Lib/test/test_pkgutil.py
+++ b/Lib/test/test_pkgutil.py
@@ -246,7 +246,11 @@
 
         for uw in unicode_words:
             d = os.path.join(self.dirname, uw)
-            os.makedirs(d, exist_ok=True)
+            try:
+                os.makedirs(d, exist_ok=True)
+            except  UnicodeEncodeError:
+                # When filesystem encoding cannot encode uw: skip this test
+                continue
             # make an empty __init__.py file
             f = os.path.join(d, '__init__.py')
             with open(f, 'w') as f: