Binary numbers starting with 0b

[Marc Khouzam]

> From: Daniel Jacobowitz
> > Or maybe there was a backwards compatibility concern?  I actually am a bit worried
> > about adding the 0b as not being backwards compatible, although I do think it would
> > be a nice thing for GDB to accept.
> 
> No, there was no decision against it.  I still think it's a good idea,
> I just didn't have time to update the parsers.
> 
> I do not see any compatibility problems.

I'm not sure what is considered bacwards-compatible but I figured
that if this patch broke the test suite, then there was some compatibility issue :-)
One example is if a frontend prepends binary numbers with 0b to display to the user;
they may now end up with 0b0b1010 if they didn't first check for the presence of 0b.
But maybe this is being overly careful.  

I still vote for the 0b, though.

Thanks

Marc