vim-patch:8.2.3584: "verbose set efm" reports location of the :compiler command

Problem:    "verbose set efm" reports the location of the :compiler command.
            (Gary Johnson)
Solution:   Add the "-keepscript" argument to :command and use it when
            defining CompilerSet.
58ef8a31d7

src/nvim/api/keysets.lua

@@ -44,6 +44,7 @@ return {
     "count";
     "desc";
     "force";
+    "keepscript";
     "nargs";
     "range";
     "register";