[dia] Add C++ guards, to make wmf plug-in link on win32

[Hans Breuer <hans src gnome org>]

commit feeefe286b7aa9184c78241fc43a10453b8397bd
Author: Hans Breuer <hans breuer org>
Date:   Sun Mar 27 12:28:59 2011 +0200

    Add C++ guards, to make wmf plug-in link on win32
    
    This is a fix for the fix:
    
    Commit:15dd90da6635d5d8d36546f6a0524f6c03c30179
    * Newer gcc chokes on cascaded extern "C"
    error: template with C linkage ...

 lib/dia_image.h |    3 +++
 lib/font.h      |    3 +++
 2 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/lib/dia_image.h b/lib/dia_image.h
index 95c0a5e..cecccb3 100644
--- a/lib/dia_image.h
+++ b/lib/dia_image.h
@@ -24,6 +24,7 @@
 
 #include "geometry.h"
 
+G_BEGIN_DECLS
 
 void dia_image_init(void);
 
@@ -57,5 +58,7 @@ const guint8 *dia_image_rgba_data(const DiaImage *image);
 const char *dia_image_filename(const DiaImage *image);
 const GdkPixbuf* dia_image_pixbuf (const DiaImage *image);
 
+G_END_DECLS
+
 #endif /* DIA_IMAGE_H */
 
diff --git a/lib/font.h b/lib/font.h
index 741a386..28a4e86 100644
--- a/lib/font.h
+++ b/lib/font.h
@@ -25,6 +25,8 @@
 #include "dia-enums.h"
 #include "geometry.h"
 
+G_BEGIN_DECLS
+
 /* Do NOT put these strings through the .po mechanism. If you need to add
    non-Roman alternatives, please insert them in the list */
 #define BASIC_SANS_FONT "arial, helvetica, helv, sans"
@@ -199,5 +201,6 @@ real* dia_font_get_sizes(const char* string, DiaFont *font, real height,
 /* -------- Font and string functions - scaled versions.
    Use these version in Renderers, exclusively. */
 
+G_END_DECLS
 
 #endif /* FONT_H */