With this patch the 'GNU Project Debugger' (GDB) can be built for Noux.
The included run script connects GDB and GDB monitor via a cross-link
terminal and allows interactive source-level debugging of the GDB monitor
test application on Genode.
Fixes#280.
In addition to autogen and autoconf, the tool-chain build script
requires ncurses (for building GDB), wget (to download the tool-chain
source code), and texinfo. Let the tool check if these packages are
installed instead of failing later during the build.