The 2nd patch (RFC for now) is meant to address a regression
reported on the list under "Problems with APIC on versions 4.9
and later (4.8 works)". In the course of analyzing output from
a debugging patch I ran into another anomaly again, which I
thought I should finally try to address. Hence patch 1.

1: change initiation of the calibration timer
2: don't move TSC backwards in time_calibration_tsc_rendezvous()

Jan