patch 9.0.0960: error when using the "Spelling / Find More Languages" menu

Problem:    Error when using the "Tools / Spelling / Find More Languages"
            menu.
Solution:   Remove "<SID>".  Reset "g:menutrans_set_lang_to" when 'encoding'
            changes. (closes #11625)
diff --git a/runtime/menu.vim b/runtime/menu.vim
index ab509a6..59fa126 100644
--- a/runtime/menu.vim
+++ b/runtime/menu.vim
@@ -474,7 +474,7 @@
   an <silent> 40.335.270 &Tools.&Spelling.&Find\ More\ Languages	:call <SID>SpellLang()<CR>
 
   let s:undo_spelllang = ['aun &Tools.&Spelling.&Find\ More\ Languages']
-  def s:SpellLang()
+  def s:SpellLang(encChanged = false)
     for cmd in s:undo_spelllang
       exe "silent! " .. cmd
     endfor
@@ -482,7 +482,8 @@
 
     var enc = &enc == "iso-8859-15" ? "latin1" : &enc
 
-    if !exists("g:menutrans_set_lang_to")
+    # Reset g:menutrans_set_lang_to when called for the EncodingChanged event.
+    if !exists("g:menutrans_set_lang_to") || encChanged
       g:menutrans_set_lang_to = 'Set Language to'
     endif
 
@@ -510,12 +511,12 @@
     else
       echomsg "Found " .. found .. " more spell files"
     endif
+
     # Need to redo this when 'encoding' is changed.
     augroup spellmenu
-    au! EncodingChanged * call <SID>SpellLang()
+    au! EncodingChanged * call SpellLang(true)
     augroup END
   enddef
-
 endif
 
 " Tools.Fold Menu