[gmime] Fix typo

[Vadim Rutkovsky <vrutkovsky src gnome org>]

commit 8fdfb77bcdfcb2e53d8223f54511958a51fcf5b7
Author: Vadim Rutkovsky <vrutkovs redhat com>
Date:   Sun May 25 11:41:44 2014 +0200

    Fix typo

 gmime/gmime-part.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gmime/gmime-part.c b/gmime/gmime-part.c
index 9aafa9f..b37c53d 100644
--- a/gmime/gmime-part.c
+++ b/gmime/gmime-part.c
@@ -824,7 +824,7 @@ g_mime_part_is_attachment (GMimePart *mime_part)
        
        disposition = g_mime_object_get_content_disposition ((GMimeObject *) mime_part);
        
-       return disposition != null && g_mime_content_disposition_is_attachment (disposition);
+       return disposition != NULL && g_mime_content_disposition_is_attachment (disposition);
 }