Bug#27081349 UNEXPECTED BEHAVIOUR WHEN DELETE WITH SPATIAL

                      FUNCTION

Fixed missing null pointer check.

Change-Id: I4be3ed1274a87af0c802dacc9345affb8185eb90

Author: Ajo Robert

sql/gcalc_slicescan.h

@@ -144,6 +144,8 @@ class Gcalc_heap : public Gcalc_dyn_list
     Info *result= (Info *)new_item();
     if (!result)
       return NULL;
+    if (!m_hook)
+      return NULL;
     *m_hook= result;
     m_hook= &result->next;
     m_n_points++;