* mi/mi-main.c: Include <sys/resource.h> if present.

* mi/mi-main.c: Include <sys/resource.h> if present.
(rusage): Declare if HAVE_GETRUSAGE.
(current_command_ts, do_timings): New static variables.
(timestamp, print_diff_now, print_diff, timeval_diff):
New static timing functions.
(mi_cmd_enable_timings): New function for new MI command.
(captured_mi_execute_command, mi_execute_async_cli_command):
Call timing functions.

* mi/mi-cmds.c (mi_cmds): Add entry for new MI command
-enable-timings.

* mi/mi-cmds.h (mi_cmd_enable_timings): New extern.

* mi/mi-parse.h: (mi_timestamp): New structure.
(mi_parse): Add mi_timestamp* member.