GDB built with Guile won't start when boot-9 is unavailable.

[Eli Zaretskii]

> From: Doug Evans <xdje42@gmail.com>
> Cc: gdb-patches@sourceware.org
> Date: Sun, 10 Aug 2014 12:11:28 -0700
> 
> There's still a problem here, as evidenced by requests to have gdb
> more tolerant, e.g., of missing Python.
> Same reasoning applies to Guile.

Indeed.