[RFA/doco] Document set/show debug aix-solib.

[Eli Zaretskii]

> From: Joel Brobecker <brobecker@adacore.com>
> Date: Tue,  7 May 2013 11:34:16 +0400
> 
> Hello,
> 
> As Pedro said, new commands should be documented. So here is a first
> try at it:
> 
> gdb/doc/ChangeLog:
> 
>         * gdb.texinfo (Debugging Output): Add documentation of
>         "set debug aix-solib" and "show debug aix-solib" commands.
> 
> Tested by rebuilding on x86_64-linux. OK to commit?

Yes, thanks.