Emacs section of Gdb Manual

[Andrew Cagney]

> It could be updated but as the Emacs manual has a relevant section 
> (Emacs-> Building-> Debuggers) and its interaction with Gdb is evolving,
> I suggest that the Gdb manual refers to this section.
> 
> I will be happy to rewrite/update this page if anyone wishes.

Woulda common section be possible?  Something that both the EMACS and 
GDB manuals could share (well, ok GDB would steal from EMACS)? 
Something like the readline chapter.

Andrew