opkg: add minion reboot & service restart support
opkg: add minion reboot & service restart support

Some packages on NILRT systems, especially kernel modules which are a
poignant exception in the Linux world for this use case, require
rebooting the minion after an opkg install/remove/upgrade/etc.

This adds support for tracking kernel module states to know when a
system reboot is necessary (via restartcheck) and calls a 'witness'
function to set a temporary 'reboot required' state which is cleared
on boot.

If restartcheck output indicates services require restart without
rebooting the system, said services are restarted without calling the
'reboot witness'.

Signed-off-by: Ioan-Adrian Ratiu <7ec73abcfe099fc5574c01312b62768070c80980@ni.com>

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt