simlpe patch implements eval command (with printf-like format and args)

[Eli Zaretskii]

> Date: Thu, 21 Feb 2008 11:20:27 +0200
> From: "Yakov Lerner" <iler.ml@gmail.com>
> 
> This simple patch implements eval command with printf-like syntax:
> 
>         eval "printf-like-format", comma-separated args

Thanks.

This new command will need documentation patch for the GDB manual
(gdb/doc/gdb.texinfo) and an entry for gdb/NEWS announcing its
addition.  (You can wait till the code is approved, if you don't want
to risk the chance that the code will not be accepted for some
reason.)