[RFC] gdb/674: GDB/MI No way to know the current selected thread(fwd)

[Keith Seitz <keiths at redhat dot com>]

---------- Forwarded message ----------
>Number:         674
>Category:       gdb
>Synopsis:       GDB/MI No way to know the current selected thread
>Description:
-thread-list-ids does not  indicate which is the selected thread

For example, with "info threads" a little star "*" will say who is
the current thread.
---------- end forwarded message ----------

Would it be acceptable to change do_captured_list_thread_ids so that for 
newer MI versions (>=2) we simply append the current thread to the output?

Now:
^done,thread-ids={thread-id="1",thread-id="2",thread-id="3"},number-of-threads="3"

[BTW, is number-of-threads really necessary? When will number-of-threads 
differ from the number of thread-ids listed?]

Proposed change:
^done,thread-ids={thread-id="1",thread-id="2",thread-id="3"},number-of-threads="3",current_thread="1"

I guess we should also change to use ui_out_list_begin/end instead of 
ui_out_tuple_begin/end?

Keith