[PATCH] print '--with{,out}-babeltrace' in 'gdb --configuration'

[Eli Zaretskii]

> Date: Wed, 17 Apr 2013 10:54:10 +0800
> From: Yao Qi <yao@codesourcery.com>
> CC: Eli Zaretskii <eliz@gnu.org>, gdb-patches <gdb-patches@sourceware.org>
> 
> The "relocatable" is unclear to me unless I checked configure.ac and 
> previous discussions.

I will add something to explain that, assuming I will find a way to
say that concisely.