targets/amd64/SS4200: add patch to detect and mitigate clockskew issues on boot

targets/amd64/SS4200: add patch to detect and mitigate clockskew issues on boot

If the machine's clock is reset to before the firmware image was
assmbled (bad cmos battery), a subsequent save will wipe out all changes
made since boot, as those files will be dated prior to the anchor file.
This patch detects that condition as soon as the /conf filesystem is
moutned, and force-sets the clock to a time 60 seconds after the most
recent mtime of the anchor file, the base confpack, or the saved
confpack (/conf/default).