RFC: objdump: Add --debug-dir=<DIR> option

[Nick Clifton]

Hi H-P,

>> or suggestions for improvements
> 
> ..."perhaps it should be a :-separated set of paths?", then "but
> that should be a separate, future change; a separate option".

I did think about doing that initially.  But in the end I decided
against it because a) it makes the code more complicated and b)
how often will a user need to specify multiple directories for
debug info files ?  I mean yes, I can imagine some scenarios where
it could be needed, but they are pretty far fetched...

Cheers
   Nick