ddebug: implement pipelined hang detection mode

ddebug: implement pipelined hang detection mode

For good performance while being able to generate decent hang reports.
The report doesn't contain the parsed IB and the buffer list, but it
isolates the draw call and dumps shaders while not having to flush
the context.

This is for GPU hangs that are harder to reproduce and require interactive
playing for minutes or even hours.

dd_pipe.h explains some implementation details. Initializing, copying
(recording) and clearing states is most of the code.

The performance should be at least 50% of the normal performance depending
on the circumstances. (i.e. 50% is expected to be the worst case scenario,
not the best case) The majority of time is spent in
dump_debug_state(PIPE_DUMP_CURRENT_SHADERS) and that's after all
the optimizations in later patches. There is no obvious way to optimize
that further.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>