Use sysconfdir variable if was given via '--sysconfdir' flag to configure script.

configure.in

@@ -28,7 +28,6 @@ else
 fi
 AC_DEFINE_UNQUOTED(PREFIX, "$EDE_INSTALL_DIR", [Default installation place])
 
-
 EDE_OPTIM_FLAGS=""
 EDE_DEBUG_FLAGS=""
 
@@ -242,6 +241,9 @@ else
 	AC_MSG_RESULT(no)
 fi
 
+dnl expand variables before EDE_INIT_JAM convert them to jam variables
+EDE_EXPAND(sysconfdir, "NONE", my_sysconfdir)
+
 EDE_INIT_JAM
 
 AC_SUBST(EDE_VERSION)
@@ -258,6 +260,7 @@ AC_SUBST(CURL_CFLAGS)
 AC_SUBST(CURL_LIBS)
 AC_SUBST(LARGEFILE)
 AC_SUBST(XKB_LIBS)
+AC_SUBST(my_sysconfdir)
 
 AC_OUTPUT([
  Jamconfig

data/startede.in

@@ -14,6 +14,7 @@
 # http://standards.freedesktop.org/basedir-spec/basedir-spec-0.6.html
 
 PREFIX="@prefix@"
+SYSCONFDIR="@my_sysconfdir@"
 
 if [ "x$XDG_DATA_HOME" = "x" ]; then
 	XDG_DATA_HOME="$HOME/.local/share"
@@ -32,7 +33,7 @@ if [ "x$XDG_DATA_DIRS" = "x" ]; then
 fi
 
 if [ "x$XDG_CONFIG_DIRS" = "x" ]; then
-	XDG_CONFIG_DIRS="$PREFIX/etc/xdg"
+	XDG_CONFIG_DIRS="$SYSCONFDIR/xdg"
 fi
 
 # prefix for applications.menu

m4/expand.m4

@@ -0,0 +1,12 @@
+dnl
+dnl found in https://jim.sh/svn/jim/vendor/sdcc/2.5.0/configure.in
+dnl Examples: AC_EXPAND(prefix, "/usr/local", expanded_prefix)
+
+AC_DEFUN([EDE_EXPAND], [
+	test "x$prefix" = xNONE && prefix="$ac_default_prefix"
+	test "x$exec_prefix" = xNONE && exec_prefix='${prefix}'
+	ac_expand=[$]$1
+	test "x$ac_expand" = xNONE && ac_expand="[$]$2"
+	ac_expand=`eval echo [$]ac_expand`
+	$3=`eval echo [$]ac_expand`
+])