* breakpoint.c (add_catch_command): Use completer_ftype.

	* breakpoint.c (add_catch_command): Use completer_ftype.
	* breakpoint.h: Include command.h.
	(add_catch_command): Use completer_ftype.
	* cli/cli-decode.c (set_cmd_completer): Use completer_ftype.
	* cli/cli-decode.h (struct cmd_list_element) <completer>:
	Use completer_ftype.
	* command.h (completer_ftype): New typedef.
	(set_cmd_completer): Use it.
	* python/py-cmd.c (struct cmdpy_completer) <completer>: Use
	completer_ftype.