Issue #16714: use 'raise' exceptions, don't 'throw'.

Patch by Serhiy Storchaka.
diff --git a/Lib/runpy.py b/Lib/runpy.py
index 7cb4668..a14a62e 100644
--- a/Lib/runpy.py
+++ b/Lib/runpy.py
@@ -211,7 +211,7 @@
                 pass
         else:
             # The following check looks a bit odd. The trick is that
-            # NullImporter throws ImportError if the supplied path is a
+            # NullImporter raises ImportError if the supplied path is a
             # *valid* directory entry (and hence able to be handled
             # by the standard import machinery)
             try: