Update runtime files.

runtime/spell/README.txt

@@ -72,7 +72,7 @@ This procedure should work well:
    change too much, the OpenOffice people are not stupid.  However, you may
    want to remove obvious mistakes.  And remove single-letter words that
    aren't really words, they mess up the suggestions (English has this
-   problem).  You can use the "fixdup" Vim script to find duplicate words.
+   problem).  You can use the "fixdup.vim" Vim script to find duplicate words.
 
 3. Make the diff file.  "aap diff" will do this for you.  If a diff would be
    too big you might consider writing a Vim script to do systematic changes.

runtime/spell/fixdup.vim

@@ -0,0 +1,27 @@
+" Vim script to fix duplicate words in a .dic file  vim: set ft=vim:
+"
+" Usage: Edit the .dic file and source this script.
+
+let deleted = 0
+
+" Start below the word count.
+let lnum = 2
+while lnum <= line('$')
+  let word = getline(lnum)
+  if word !~ '/'
+    if search('^' . word . '/', 'w') != 0
+      let deleted += 1
+      exe lnum . "d"
+      continue		" don't increment lnum, it's already at the next word
+    endif
+  endif
+  let lnum += 1
+endwhile
+
+if deleted == 0
+  echomsg "No duplicate words found"
+elseif deleted == 1
+  echomsg "Deleted 1 duplicate word"
+else
+  echomsg printf("Deleted %d duplicate words", deleted)
+endif