Add observer and runtime_tools in releases when --enable-tools

When --enable-tools, include observer and runtime_tools
in the OTP releases, as they are required by "ejabberdctl etop".

With this fix, "ejabberdctl etop" works correctly when:
* rebar3 + make rel
* mix + make dev
* mix + make rel

.github/workflows/runtime.yml

@@ -68,6 +68,7 @@ jobs:
                     --prefix=/tmp/ejabberd \
                     --enable-all \
                     --disable-elixir \
+                    --disable-tools \
                     --disable-odbc
         make update
         make

configure.ac

@@ -254,7 +254,7 @@ AC_ARG_ENABLE(system_deps,
 esac],[if test "x$system_deps" = "x"; then system_deps=false; fi])
 
 AC_ARG_ENABLE(tools,
-[AS_HELP_STRING([--enable-tools],[build development tools (default: no)])],
+[AS_HELP_STRING([--enable-tools],[build development tools: ejabberd-po, etop (default: no)])],
 [case "${enableval}" in
   yes) tools=true ;;
   no)  tools=false ;;

mix.exs

@@ -145,7 +145,9 @@ defmodule Ejabberd.MixProject do
   end
 
   defp cond_apps do
-    for {:true, app} <- [{config(:stun), :stun}], do:
+    for {:true, app} <- [{config(:stun), :stun},
+                         {config(:tools), :observer},
+                         {config(:tools), :runtime_tools}], do:
       app
   end
 

src/ejabberd.app.src.script

@@ -6,10 +6,14 @@
             {elixir, true} -> [elixir, iex, logger, mix];
             _ -> []
         end,
+        Tools = case lists:keyfind(tools, 1, Terms) of
+            {tools, true} -> [observer, runtime_tools]; % for `ejabberdctl etop`
+            _ -> []
+        end,
         {[lists:keyfind(description, 1, Terms),
          lists:keyfind(vsn, 1, Terms),
          {env, [{enabled_backends, EBs}]}
-        ], Elixirs};
+        ], Elixirs ++ Tools};
     _Err ->
         {[], []}
     end,