vim-patch:8.1.1542: an OptionSet autocommand does not get enough info

Problem:    An OptionSet autocommand does not get enough info.
Solution:   Add v:option_command, v:option_oldlocal and v:option_oldglobal.
            (Latrice Wilgus, closes vim/vim#4118)
d7c9687947

src/nvim/eval.h

@@ -138,6 +138,9 @@ typedef enum {
   VV_COMPLETED_ITEM,
   VV_OPTION_NEW,
   VV_OPTION_OLD,
+  VV_OPTION_OLDLOCAL,
+  VV_OPTION_OLDGLOBAL,
+  VV_OPTION_COMMAND,
   VV_OPTION_TYPE,
   VV_ERRORS,
   VV_FALSE,