Fix #383: configure must expand FINIT_RUNPATH_ before define

This fixes an annying buglet that creeped in just before the v4.5 release
causing none of the internal services to be registered properly:

    conf_save_service():Failed creating ${localstatedir}/run/finit/system/dbus.conf: No such file or directory
    plugin_run_hook():Calling modules-load hook n:o 5 (arg: 0x55c4c8133621) ...
    load():Scanning /etc/modules-load.d for config files ...
    cond_set_oneshot():hook/svc/plugin
    cond_set_oneshot_noupdate():hook/svc/plugin => /run/finit/cond/hook/svc/plugin
    cond_update():hook/svc/plugin
    parse_conf():*** Parsing /etc/finit.conf
    conf_save_service():Failed creating ${localstatedir}/run/finit/system/runparts.conf: No such file or directory

The fix, like most, is simple when you find it.  We must expand $runstatedir
before creating the #define in config.h

For convenience, here's the patch for the generated configure script:

&<---------------------------[cut here]---------------------------
--- a/configure	2023-11-05 23:39:51.907334321 +0100
+++ b/configure	2023-11-05 23:39:58.339299795 +0100
@@ -15352,7 +15352,15 @@
 printf "%s\n" "#define FINIT_EXECPATH_ \"$pkglibexecdir\"" >>confdefs.h

-printf "%s\n" "#define FINIT_RUNPATH_ \"$runstatedir/finit/system\"" >>confdefs.h
+	finit_runpath="$runstatedir/finit/system"
+	finit_runpath=`(
+	    test "x$prefix" = xNONE && prefix="$ac_default_prefix"
+	    test "x$exec_prefix" = xNONE && exec_prefix="${prefix}"
+	    eval echo \""$finit_runpath"\"
+	    )`
+
+
+printf "%s\n" "#define FINIT_RUNPATH_ \"$finit_runpath\"" >>confdefs.h

&<---------------------------[cut here]---------------------------
Ensure you include the three empty lines for context at the end!

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

configure.ac

@@ -314,7 +314,8 @@ pkglibdir=$libdir/finit
 AC_SUBST(pkglibexecdir)
 AC_EXPAND_DIR(pkglibexecdir, "$libexecdir/finit")
 AC_DEFINE_UNQUOTED(FINIT_EXECPATH_, "$pkglibexecdir", [Finit libexec path])
-AC_DEFINE_UNQUOTED(FINIT_RUNPATH_, "$runstatedir/finit/system", [Finit runtime dynamic system services])
+AC_EXPAND_DIR(finit_runpath, "$runstatedir/finit/system")
+AC_DEFINE_UNQUOTED(FINIT_RUNPATH_, "$finit_runpath", [Finit runtime dynamic system services])
 
 AC_EXPAND_DIR(plugin_path, "$pkglibdir/plugins")
 AC_SUBST(plugin_path)