Do something sensible for timestamp wrapping.

Do something sensible for timestamp wrapping.

Before we had this result in our frame timings (with the after/before
counters printed):

0x0000000fffa65090 0x0000000ffea7f9a0
frame: 99 16.6684 16.4952 0.0195919 0
0x0000000000a540a0 0x0000000fffa65090
frame: 100 1.84467e+13 1.84467e+13 1.7174e-14 0
0x0000000001a2fd30 0x0000000000a540a0
frame: 101 16.6289 16.4461 0.0216595 0

And now we get:

0x0000000fff3ab690 0x0000000ffe3c4f10
frame: 2387 16.6726 16.609 0.0173506 0
0x000000000038b420 0x0000000fff3ab690
frame: 2388 16.6455 16.5858 0.0169653 0
0x000000000137b4c0 0x000000000038b420
frame: 2389 16.7118 16.6509 0.0168314 0