Use counted_command_line everywhere

Use counted_command_line everywhere

Currently command lines are reference counted using shared_ptr only
when attached to breakpoints.  This patch changes gdb to use
shared_ptr in commands as well.  This allows for the removal of
copy_command_lines.

Note that the change to execute_user_command explicitly makes a new
reference to the command line.  This will be used in a later patch.

This simplifies struct command_line based on the observation that a
given command can have at most two child bodies: an "if" can have both
"then" and "else" parts.  Perhaps the names I've chosen for the
replacements here are not very good -- your input requested.

ChangeLog
2018-05-04  Tom Tromey  <tom@tromey.com>

	* tracepoint.c (all_tracepoint_actions): Rename from
	all_tracepoint_actions_and_cleanup.  Change return type.
	(actions_command, encode_actions_1, encode_actions)
	(trace_dump_actions, tdump_command): Update.
	* remote.c (remote_download_command_source): Update.
	* python/python.c (gdbpy_eval_from_control_command)
	(python_command, python_interactive_command): Update.
	* mi/mi-cmd-break.c (mi_cmd_break_commands): Update.
	* guile/guile.c (guile_command)
	(gdbscm_eval_from_control_command, guile_command): Update.
	* compile/compile.c (compile_code_command)
	(compile_print_command, compile_to_object): Update.
	* cli/cli-script.h (struct command_lines_deleter): New.
	(counted_command_line): New typedef.
	(struct command_line): Add constructor, destructor.
	<body_list>: Remove.
	<body_list_0, body_list_1>: New members.
	(command_line_up): Remove typedef.
	(read_command_lines, read_command_lines_1, get_command_line):
	Update.
	(copy_command_lines): Don't declare.
	* cli/cli-script.c (build_command_line): Use "new".
	(get_command_line): Return counted_command_line.
	(print_command_lines, execute_user_command)
	(execute_control_command_1, while_command, if_command): Update.
	(realloc_body_list): Remove.
	(process_next_line, recurse_read_control_structure): Update.
	(read_command_lines, read_command_lines_1): Return counted_command_line.
	(free_command_lines): Use "delete".
	(copy_command_lines): Remove.
	(define_command, document_command, show_user_1): Update.
	* cli/cli-decode.h (struct cmd_list_element) <user_commands>: Now
	a counted_command_line.
	* breakpoint.h (counted_command_line): Remove typedef.
	(breakpoint_set_commands): Update.
	* breakpoint.c (check_no_tracepoint_commands)
	(validate_commands_for_breakpoint): Update.
	(breakpoint_set_commands): Change commands to be a
	counted_command_line.
	(commands_command_1, update_dprintf_command_list)
	(create_tracepoint_from_upload): Update.