[glib] glib/gvariant.c: Fix NULL pointer check in is_valid_heap_iter

[Colin Walters <walters src gnome org>]

commit 1be86b3d185cfc64bd355c1afd958b1757a1761a
Author: Yury Usishchev <yury usischev phystech edu>
Date:   Thu Jul 28 00:41:38 2016 +0300

    glib/gvariant.c: Fix NULL pointer check in is_valid_heap_iter
    
    https://bugzilla.gnome.org/show_bug.cgi?id=769245

 glib/gvariant.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/glib/gvariant.c b/glib/gvariant.c
index 40f58c1..c311da6 100644
--- a/glib/gvariant.c
+++ b/glib/gvariant.c
@@ -2916,8 +2916,8 @@ struct heap_iter
 #define GVHI_MAGIC              ((gsize) 1450270775u)
 #define is_valid_iter(i)        (i != NULL && \
                                  GVSI(i)->magic == GVSI_MAGIC)
-#define is_valid_heap_iter(i)   (GVHI(i)->magic == GVHI_MAGIC && \
-                                 is_valid_iter(i))
+#define is_valid_heap_iter(i)   (is_valid_iter(i) && \
+                                 GGVHI(i)->magic == GVHI_MAGIC)
 
 /**
  * g_variant_iter_new: