* mi/mi-cmds.h (mi_execute_command): Make "cmd" const.
	* mi/mi-interp.c (mi_interpreter_exec): Make "command" const.
	Remove temporary copy of input string.
	(mi_execute_command_wrapper): Make "cmd" const.
	* mi/mi-main.c (mi_execute_command): Make "string_ptr" const.
	* mi/mi-parse.c (mi_parse_argv): Make "args" const.
	Use const strings.
	(mi_parse): Make "cmd" const.
	Use const strings.
	* mi/mi-parse.h (mi_parse): Make "cmd" const.