When matching the 'label' session argument using '<if-args>' in a
routing table, we can omit the child name prefix because it is always
the same for all sessions originating from the child anyway. Therefore,
this patch adds a special case for matching session labels. It makes the
expression of label-specific routing more intuitive.
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.
