win32: silence build warning

glocalfileinfo.c: In function '_g_local_file_info_get':
glocalfileinfo.c:1955:11: warning: passing argument 3 of
'get_thumbnail_attributes' from incompatible pointer type [enabled by
default]
           get_thumbnail_attributes (path, info, &statbuf);
           ^
glocalfileinfo.c:1285:1: note: expected 'const struct GStatBuf *' but
argument is of type 'struct _stati64 *'
 get_thumbnail_attributes (const char     *path,

https://bugzilla.gnome.org/show_bug.cgi?id=711547

gio/glocalfileinfo.c

@@ -1283,7 +1283,7 @@ get_content_type (const char          *basename,
 static void
 get_thumbnail_attributes (const char     *path,
                           GFileInfo      *info,
-                          const GStatBuf *stat_buf)
+                          const GLocalFileStat *stat_buf)
 {
   GChecksum *checksum;
   char *uri;