vim-patch:9.0.0342: ":wincmd =" equalizes in two directions

Problem:    ":wincmd =" equalizes in two directions.
Solution:   Make ":vertical wincmd =" equalize vertically only and
            ":horizontal wincmd =" equalize horizontally only.
21c3a80a7f

src/nvim/ex_cmds.lua

@@ -1140,6 +1140,12 @@ module.cmds = {
     addr_type='ADDR_NONE',
     func='ex_history',
   },
+  {
+    command='horizontal',
+    flags=bit.bor(NEEDARG, EXTRA, NOTRLCOM),
+    addr_type='ADDR_NONE',
+    func='ex_wrongmodifier',
+  },
   {
     command='insert',
     flags=bit.bor(BANG, RANGE, TRLBAR, CMDWIN, LOCK_OK, MODIFY),