[libpeas] Fix peas-demo plugin discovery on 64 bits platforms.

[Steve Frécinaux <sfre src gnome org>]

commit dbf7d53b80934d1ee2f7b84e8f64d6ce4357add3
Author: Steve Frécinaux <code istique net>
Date:   Thu Jul 22 15:24:45 2010 +0200

    Fix peas-demo plugin discovery on 64 bits platforms.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=625034

 peas-demo/Makefile.am |    1 +
 peas-demo/peas-demo.c |    4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/peas-demo/Makefile.am b/peas-demo/Makefile.am
index 42c4eec..acea17b 100644
--- a/peas-demo/Makefile.am
+++ b/peas-demo/Makefile.am
@@ -23,6 +23,7 @@ peas_demo_LDADD = \
 
 peas_demo_CFLAGS = \
 	$(PEAS_CFLAGS)			\
+	-DPEAS_LIBDIR="\"$(libdir)\""	\
 	-DPEAS_PREFIX="\"$(prefix)\""
 
 .PHONY: demo
diff --git a/peas-demo/peas-demo.c b/peas-demo/peas-demo.c
index cfbb8b5..877b0f3 100644
--- a/peas-demo/peas-demo.c
+++ b/peas-demo/peas-demo.c
@@ -160,14 +160,14 @@ main (int    argc,
   else
     {
       /* System-wide plugins */
-      search_paths[2] = g_strdup (PEAS_PREFIX "/lib/peas-demo/plugins/");
+      search_paths[2] = g_strdup (PEAS_LIBDIR "/peas-demo/plugins/");
       search_paths[3] = g_strdup (PEAS_PREFIX "/share/peas-demo/plugins/");
     }
 
   g_irepository_require (g_irepository_get_default (), "PeasUI", "1.0", 0, NULL);
 
   engine = peas_engine_new ("PeasDemo",
-                            PEAS_PREFIX "/lib/peas-demo/",
+                            PEAS_LIBDIR "/peas-demo/",
                             (const gchar **) search_paths);
 
   n_windows = 0;