Rebar3: Provide proper path to iex

We can't use iex variable, because rebar3/relx_overlay.erl already uses
all existing app names as variables.

Makefile.in

@@ -295,7 +295,6 @@ relive:
 
 relivelibdir=$(shell pwd)/$(DEPSDIR)
 relivedir=$(shell pwd)/_build/relive
-iexpath=$(shell which iex)
 CONFIG_DIR = ${relivedir}/conf
 SPOOL_DIR = ${relivedir}/database
 LOGS_DIR = ${relivedir}/logs
@@ -305,9 +304,9 @@ ejabberdctl.relive:
 		-e "s*{{config_dir}}*${CONFIG_DIR}*g" \
 		-e "s*{{logs_dir}}*${LOGS_DIR}*g" \
 		-e "s*{{spool_dir}}*${SPOOL_DIR}*g" \
-		-e "s*{{bindir}}/iex*$(iexpath)*g" \
 		-e "s*{{bindir}}*@bindir@*g" \
 		-e "s*{{libdir}}*${relivelibdir}${ELIXIR_LIBDIR}*g" \
+		-e "s*{{iexpath}}*@IEX@*g" \
 		-e "s*{{erl}}*@ERL@*g" \
 		-e "s*{{epmd}}*@EPMD@*g" ejabberdctl.template \
 		> ejabberdctl.relive
@@ -331,6 +330,7 @@ ejabberdctl.example: vars.config
 		-e "s*{{spool_dir}}*${SPOOLDIR}*g" \
 		-e "s*{{bindir}}*@bindir@*g" \
 		-e "s*{{libdir}}*@libdir@${ELIXIR_LIBDIR}*g" \
+		-e "s*{{iexpath}}*@IEX@*g" \
 		-e "s*{{erl}}*@ERL@*g" \
 		-e "s*{{epmd}}*@EPMD@*g" ejabberdctl.template \
 		> ejabberdctl.example

configure.ac

@@ -39,6 +39,7 @@ fi
 AC_PATH_TOOL(ERL, erl, , [${extra_erl_path}$PATH])
 AC_PATH_TOOL(ERLC, erlc, , [${extra_erl_path}$PATH])
 AC_PATH_TOOL(EPMD, epmd, , [${extra_erl_path}$PATH])
+AC_PATH_TOOL(IEX, iex, , [${extra_erl_path}$PATH])
 
 AC_ERLANG_NEED_ERL
 AC_ERLANG_NEED_ERLC

ejabberdctl.template

@@ -15,8 +15,8 @@ SCRIPT_DIR="$(cd "$(dirname "$SCRIPT")" && pwd -P)"
 # shellcheck disable=SC2034
 ERTS_VSN="{{erts_vsn}}"
 ERL="{{erl}}"
-IEX="{{bindir}}/iex"
 EPMD="{{epmd}}"
+IEX="{{iexpath}}"
 INSTALLUSER="{{installuser}}"
 
 # check the proper system user is used

mix.exs

@@ -250,7 +250,7 @@ defmodule Ejabberd.MixProject do
       logs_dir: config(:logs_dir),
       spool_dir: config(:spool_dir),
       vsn: config(:vsn),
-      iex: config(:iex),
+      iexpath: config(:iexpath),
       erl: config(:erl),
       epmd: config(:epmd),
       bindir: Path.join([config(:release_dir), "releases", version()]),

vars.config.in

@@ -53,9 +53,9 @@
 {sysconfdir, "{{release_dir}}/etc"}.
 {erts_dir, "{{release_dir}}/erts-${ERTS_VSN#erts-}"}.
 {installuser, "@INSTALLUSER@"}.
-{iex, "{{release_dir}}/releases/{{vsn}}/iex"}.
 {erl, "{{erts_dir}}/bin/erl"}.
 {epmd, "{{erts_dir}}/bin/epmd"}.
+{iexpath, "{{release_dir}}/releases/{{vsn}}/iex"}.
 {localstatedir, "{{release_dir}}/var"}.
 {libdir, "{{release_dir}}/lib"}.
 {docdir, "{{release_dir}}/doc"}.