Make the intepreters output to all UIs

Make the intepreters output to all UIs

When we have multiple consoles, MI channels, etc., then we need to
broadcast breakpoint hits, etc. to all UIs.  In the past, I've
adjusted most of the run control to communicate events to the
interpreters through observer notifications, so events would be
properly sent to console and MI streams, in sync and async modes.

This patch does the next logical step -- have each interpreter's
observers output interpreter-specific info to _all_ UIs.

Note that when we have multiple instances of active cli/tui
interpreters, then the cli_interp and tui_interp globals no longer
work.  This is addressed by this patch.

Also, the interpreters currently register some observers when resumed
and remove them when suspended.  If we have multiple instances of the
interpreters, and they can be suspended/resumed at different,
independent times, that no longer works.  What we instead do is always
install the observers, and then have the observers themselves know
when to do nothing.

An earlier prototype of this series did the looping over struct UIs in
common code, and then dispatched events to the interpreters through a
matching interp_on_foo method for each observer.  That turned out a
lot more complicated than the present solution, as we'd end up with
having to create a new interp method every time some interpreter
wanted to listen to some observer notification, resulting in a lot of
duplicated make-work and more coupling than desirable.

gdb/ChangeLog:
2016-06-21  Pedro Alves  <palves@redhat.com>

	* cli/cli-interp.c (cli_interp): Delete.
	(as_cli_interp): New function.
	(cli_on_normal_stop, cli_on_signal_received)
	(cli_on_end_stepping_range, cli_on_signal_exited, cli_on_exited)
	(cli_on_no_history): Send output to all CLI UIs.
	(cli_on_sync_execution_done, cli_on_command_error): Skip output if
	the top level interpreter is not a CLI.
	(cli_interpreter_init): Don't set cli_interp or install observers
	here.
	(_initialize_cli_interp): Install observers here.
	* event-top.c (main_ui_, ui_list): New globals.
	(current_ui): Point to main_ui_.
	(restore_ui_cleanup, switch_thru_all_uis_init)
	(switch_thru_all_uis_cond, switch_thru_all_uis_next): New
	functions.
	* mi/mi-interp.c (as_mi_interp): New function.
	(mi_interpreter_init): Don't install observers here.
	(mi_on_sync_execution_done): Skip output if the top level
	interpreter is not a MI.
	(mi_new_thread, mi_thread_exit, mi_record_changed)
	(mi_inferior_added, mi_inferior_appeared, mi_inferior_exit)
	(mi_inferior_removed): Send output to all MI UIs.
	(find_mi_interpreter, mi_interp_data): Delete.
	(find_mi_interp): New function.
	(mi_on_signal_received, mi_on_end_stepping_range)
	(mi_on_signal_exited, mi_on_exited, mi_on_no_history): Send output
	to all MI UIs.
	(mi_on_normal_stop): Rename to ...
	(mi_on_normal_stop_1): ... this.
	(mi_on_normal_stop): Reimplement, sending output to all MI UIs.
	(mi_traceframe_changed, mi_tsv_created, mi_tsv_deleted)
	(mi_tsv_modified, mi_breakpoint_created, mi_breakpoint_deleted)
	(mi_breakpoint_modified, mi_output_running_pid): Send output to
	all MI UIs.
	(mi_on_resume): Rename to ...
	(mi_on_resume_1): ... this.  Don't handle infcalls here.
	(mi_on_resume): Reimplement, sending output to all MI UIs.
	(mi_solib_loaded, mi_solib_unloaded, mi_command_param_changed)
	(mi_memory_changed): Send output to all MI UIs.
	(report_initial_inferior): Install observers here.
	* top.h (struct ui) <next>: New field.
	(ui_list): Declare.
	(struct switch_thru_all_uis): New.
	(switch_thru_all_uis_init, switch_thru_all_uis_cond)
	(switch_thru_all_uis_next): Declare.
	(SWITCH_THRU_ALL_UIS): New macro.
	* tui/tui-interp.c (tui_interp): Delete global.
	(as_tui_interp): New function.
	(tui_on_normal_stop, tui_on_signal_received)
	(tui_on_end_stepping_range, tui_on_signal_exited, tui_on_exited)
	(tui_on_no_history): Send output to all TUI UIs.
	(tui_on_sync_execution_done, tui_on_command_error): Skip output if
	the top level interpreter is not a TUI.
	(tui_init): Don't set tui_interp or install observers here.
	(_initialize_tui_interp): Install observers here.