Fix valgrind failure with Unique class

sql/sql_class.h

@@ -2990,7 +2990,7 @@ class Unique :public Sql_alloc
                                             ulonglong max_in_memory_size)
   {
     register ulonglong max_elems_in_tree=
-      (1 + max_in_memory_size / ALIGN_SIZE(sizeof(TREE_ELEMENT)+key_size));
+      max_in_memory_size / ALIGN_SIZE(sizeof(TREE_ELEMENT)+key_size);
     return (int) (sizeof(uint)*(1 + nkeys/max_elems_in_tree));
   }