Add target-side support for dynamic printf.

	Add target-side support for dynamic printf.
	* NEWS: Mention the additional style.
	* breakpoint.h (struct bp_target_info): New fields tcommands, persist.
	(struct bp_location): New field cmd_bytecode.
	* breakpoint.c: Include format.h.
	(disconnected_dprintf): New global.
	(parse_cmd_to_aexpr): New function.
	(build_target_command_list): New function.
	(insert_bp_location): Call it.
	(remove_breakpoints_pid): Skip dprintf breakpoints.
	(print_one_breakpoint_location): Ditto.
	(dprintf_style_agent): New global.
	(dprintf_style_enums): Add dprintf_style_agent.
	(update_dprintf_command_list): Add agent case.
	(agent_printf_command): New function.
	(_initialize_breakpoint): Add new commands.
	* common/ax.def (printf): New bytecode.
	* ax.h (ax_string): Declare.
	* ax-gdb.h (gen_printf): Declare.
	* ax-gdb.c: Include cli-utils.h, format.h.
	(gen_printf): New function.
	(maint_agent_print_command): New function.
	(_initialize_ax_gdb): Add maint agent-printf command.
	* ax-general.c (ax_string): New function.
	(ax_print): Add printf disassembly.
	* Makefile.in (SFILES): Add format.c
	(COMMON_OBS): Add format.o.
	* common/format.h: New file.
	* common/format.c: New file.
	* printcmd.c: Include format.h.
	(ui_printf): Call parse_format_string.
	* remote.c (remote_state): New field breakpoint_commands.
	(PACKET_BreakpointCommands): New enum.
	(remote_breakpoint_commands_feature): New function.
	(remote_protocol_features): Add new BreakpointCommands entry.
	(remote_can_run_breakpoint_commands): New function.
	(remote_add_target_side_commands): New function.
	(remote_insert_breakpoint): Call it.
	(remote_insert_hw_breakpoint): Ditto.
	(_initialize_remote): Add new packet configuration for
	target-side breakpoint commands.
	* target.h (struct target_ops): New field
	to_can_run_breakpoint_commands.
	(target_can_run_breakpoint_commands): New macro.
	* target.c (update_current_target): Handle
	to_can_run_breakpoint_commands.

	[gdbserver]
	* Makefile.in (WARN_CFLAGS_NO_FORMAT): Define.
	(ax.o): Add it to build rule.
	(ax-ipa.o): Ditto.
	(OBS): Add format.o.
	(IPA_OBS): Add format.o.
	* server.c (handle_query): Claim support for breakpoint commands.
	(process_point_options): Add command case.
	(process_serial_event): Leave running if there are printfs in
	effect.
	* mem-break.h (any_persistent_commands): Declare.
	(add_breakpoint_commands): Declare.
	(gdb_no_commands_at_breakpoint): Declare.
	(run_breakpoint_commands): Declare.
	* mem-break.c (struct point_command_list): New struct.
	(struct breakpoint): New field command_list.
	(any_persistent_commands): New function.
	(add_commands_to_breakpoint): New function.
	(add_breakpoint_commands): New function.
	(gdb_no_commands_at_breakpoint): New function.
	(run_breakpoint_commands): New function.
	* linux-low.c (linux_wait_1): Test for and run breakpoint commands
	locally.
	* ax.c: Include format.h.
	(ax_printf): New function.
	(gdb_eval_agent_expr): Add printf opcode.

	[doc]
	* gdb.texinfo (Dynamic Printf): Mention agent style and
	disconnected dprintf.
	(Maintenance Commands): Describe maint agent-printf.
	(General Query Packets): Mention BreakpointCommands feature.
	(Packets): Document commands extension to Z0 packet.
	* agentexpr.texi (Bytecode Descriptions): Document printf
	bytecode.

	[testsuite]
	* gdb.base/dprintf.exp: Add agent style tests.