package/procps-ng: use logger in S02sysctl only if it is available

package/procps-ng: use logger in S02sysctl only if it is available

The script used the logger utility unconditionally but it may not exist
(e.g. busybox-minimal.config is used and BR2_PACKAGE_UTIL_LINUX_LOGGER
is not selected).

Declare two functions to perform the operation, run_logger and run_std,
and use the appropriate one, depending on the existence of logger.

Signed-off-by: Carlos Santos <unixmania@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>