[google gcc-4_7, integration] Add more lightweight checks for dangling vectors

[Paul Pluzhnikov]

This patch sets destructed vector into an invalid state, such that
subsequent calls to begin(), end(), size(), etc. all throw logic_error.

Google ref b/7248326

Ok for google/gcc-4_7 and google/integration?

Thanks,
--
Paul Pluzhnikov

Index: libstdc++-v3/include/bits/stl_vector.h
===================================================================
--- libstdc++-v3/include/bits/stl_vector.h      (revision 195356)
+++ libstdc++-v3/include/bits/stl_vector.h      (working copy)
@@ -159,7 +159,12 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 
       ~_Vector_base()
       { _M_deallocate(this->_M_impl._M_start, this->_M_impl._M_end_of_storage
-                     - this->_M_impl._M_start); }
+                     - this->_M_impl._M_start);
+#if __google_stl_debug_dangling_vector
+        this->_M_impl._M_start = 0;
+        this->_M_impl._M_finish = reinterpret_cast<_Tp*>(~0UL);
+#endif
+      }
 
     public:
       _Vector_impl _M_impl;