Update runtime files.

runtime/pack/dist/opt/termdebug/plugin/termdebug.vim

@@ -2,7 +2,7 @@
 "
 " Author: Bram Moolenaar
 " Copyright: Vim license applies, see ":help license"
-" Last Change: 2020 Oct 28
+" Last Change: 2020 Dec 07
 "
 " WORK IN PROGRESS - Only the basics work
 " Note: On MS-Windows you need a recent version of gdb.  The one included with
@@ -726,8 +726,12 @@ func s:DeleteCommands()
   delcommand Source
   delcommand Winbar
 
-  if exists('s:k_map_saved') && !empty(s:k_map_saved)
-    call mapset('n', 0, s:k_map_saved)
+  if exists('s:k_map_saved')
+    if empty(s:k_map_saved)
+      nunmap K
+    else
+      call mapset('n', 0, s:k_map_saved)
+    endif
     unlet s:k_map_saved
   endif