corec: test array Heap has DATA_FLAG_MEMHEAP

Otherwise we won't be able to read back the cc_memheap* from
the p->_Begin shift.

corec/corec/array/array.c

@@ -126,7 +126,10 @@ void ArrayInitEx(array* p,const cc_memheap* Heap)
     if (Heap == NULL)
         p->_Begin = NULL;
     else
+    {
+        assert(Heap->Size & DATA_FLAG_MEMHEAP);
         p->_Begin = (void*)Heap->data;
+    }
     p->_Used = 0;
 }