[Win32] Be able to load plugins by providing correct build-time paths

modules/plugin-lib/Makefile.am

@@ -4,6 +4,8 @@ module_plugin_lib_la_CPPFLAGS = \
 	$(AM_CPPFLAGS)						\
 	-DG_LOG_DOMAIN=\"evolution-plugin-lib\"			\
 	-I$(top_srcdir)						\
+	-DEVOLUTION_PLUGINDIR="\"$(plugindir)\""		\
+	-DBUILDTIME_EVOLUTION_PLUGINDIR="\"$(plugindir)\""	\
 	-DEVOLUTION_PREFIX=\""$(prefix)"\"			\
 	$(EVOLUTION_DATA_SERVER_CFLAGS)				\
 	$(GNOME_PLATFORM_CFLAGS)				\

modules/plugin-lib/e-plugin-lib.c

@@ -26,6 +26,7 @@
 
 #ifdef G_OS_WIN32
 #include <libedataserver/libedataserver.h> /* for e_util_replace_prefix() */
+#include "e-util/e-util-private.h"
 #endif
 
 #include <string.h>
@@ -153,8 +154,8 @@ plugin_lib_construct (EPlugin *plugin,
 	{
 		gchar *mapped_location =
 			e_util_replace_prefix (
-				EVOLUTION_PREFIX,
-				e_util_get_prefix (),
+				BUILDTIME_EVOLUTION_PLUGINDIR,
+				EVOLUTION_PLUGINDIR,
 				plugin_lib->location);
 		g_free (plugin_lib->location);
 		plugin_lib->location = mapped_location;