commands: dhrystone: remove unneeded and out-of-place <stdbool.h> ...

Our bool definitions come out of <linux/types.h>. <stdbool.h> shouldn't
be used for normal barebox code. We already include <linux/types.h> by
means of <common.h> above. So drop the <stdbool.h>

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

commands/*: Replace license and copyright boilerplate by SPDX identfiers ...

While at it also drop references to the non-existing CREDITS file and do
some small rearrangements for some uniform formatting.
(SPDX-License-Identifier first, then copyright texts and then an empty
line.)

The advantage is that these specifiers are machine-parseable which helps
license conformance.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

dhrystone: Fix documentation ...

BAREBOX_CMD_HELP_TEXT may not contain a linebreak.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

commands: Add dhrystone ...

This tool will help to measure the system performance.

Some SoCs haven't the possibility to route their clocks to the output pins.
So you can use dhrystone to get a feedback about the clock speed.

Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>