Specify mnesia dir for `make run` command

test/run_emqx.escript

@@ -4,6 +4,10 @@ main(_) ->
     start().
 
 start() ->
+    ok = application:load(mnesia),
+    MnesiaName = lists:concat(["Mnesia.", atom_to_list(node())]),
+    MnesiaDir = filename:join(["_build", "data", MnesiaName]),
+    ok = application:set_env(mnesia, dir, MnesiaDir),
     SpecEmqxConfig = fun(_) -> ok end,
     start(SpecEmqxConfig).