use std::size_t

Author: kroening

src/goto-programs/interpreter_class.h

@@ -47,7 +47,7 @@ class interpretert
   typedef std::vector<memory_cellt> memoryt;
   memoryt memory;
 
-  unsigned stack_pointer;
+  std::size_t stack_pointer;
 
   void build_memory_map();
   void build_memory_map(const symbolt &symbol);