Set ETS table heir, so ext_mod process inherits the table

An ETS table is automatically destroyed when its parent process dies.
When mod_cron is installed using the module_install command,
the calling process dies immediately, and ETS table gets destroyed.

That problem didn't appear when the module is already installed
and configured when ejabberd starts: in that case the calling process
is ext_mod, which is always alive.

mod_cron/src/mod_cron.erl

@@ -36,7 +36,8 @@ start(Host, Opts) ->
     ejabberd_hooks:add(webadmin_menu_host, Host, ?MODULE, web_menu_host, 50),
     ejabberd_hooks:add(webadmin_page_host, Host, ?MODULE, web_page_host, 50),
     Tasks = gen_mod:get_opt(tasks, Opts),
-    catch ets:new(cron_tasks, [ordered_set, named_table, public, {keypos, 2}]),
+    Heir = {heir, whereis(ext_mod), ?MODULE},
+    catch ets:new(cron_tasks, [ordered_set, named_table, public, {keypos, 2}, Heir]),
     [add_task(Host, Task) || Task <- Tasks],
     ok.
 

mod_webpresence/src/mod_webpresence.erl

@@ -58,7 +58,8 @@ start(Host, Opts) ->
               PP ->
                   PP
           end,
-    catch ets:new(pixmaps_dirs, [named_table, public]),
+    Heir = {heir, whereis(ext_mod), ?MODULE},
+    catch ets:new(pixmaps_dirs, [named_table, public, Heir]),
     ets:insert(pixmaps_dirs, {directory, Dir}),
     case gen_mod:start_child(?MODULE, Host, Opts) of
        {ok, Ref} ->