[google gcc-4_7, integration] Add lightweight checks for front()/back() on empty vector

[Diego Novillo]

On Sun, Jan 20, 2013 at 1:15 PM, Paul Pluzhnikov <ppluzhnikov@google.com> wrote:
> On Sun, Jan 20, 2013 at 3:16 AM, Gerald Pfeifer <gerald@pfeifer.com> wrote:
>> Isn't the error message wrong, then?
>
> Thanks for catching that! Updated patch attached.

OK for google branches.


Diego.