[dia] wmf: fix plug-in version check

[Hans Breuer <hans src gnome org>]

commit 205aacbdf45de70b72130c14f9b2ad8e3970fae9
Author: Hans Breuer <hans breuer org>
Date:   Tue Nov 1 12:47:43 2011 +0100

    wmf: fix plug-in version check
    
    The plug-in version check function was exported with a mangled name,
    making the check not finding it. Wrapping the DIA_PLUGIN_CHECK_INIT
    with extern "C" {} fixes it - at least for msvc.

 plug-ins/wmf/wmf.cpp |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/plug-ins/wmf/wmf.cpp b/plug-ins/wmf/wmf.cpp
index 5a1e55d..a417029 100644
--- a/plug-ins/wmf/wmf.cpp
+++ b/plug-ins/wmf/wmf.cpp
@@ -1501,8 +1501,9 @@ static DiaCallbackFilter cb_gdi_print = {
 #endif
 
 /* --- dia plug-in interface --- */
-
+extern "C" {
 DIA_PLUGIN_CHECK_INIT
+}
 
 PluginInitResult
 dia_plugin_init(PluginInfo *info)