debugger: fix breakage with gdb 7.1

Officially we support only 7.2+ nowadays, but 7.1 used to work. This was
broken recently by the "dynamic type" work. With this patch the debugger
behaves as before with 7.1, and shows dynamic types with 7.2+.

Change-Id: Id9e775d19712ea40d7c2a7aa8f9f734174d2446e
Reviewed-by: hjk <qthjk@ovi.com>