So, I took a look at the "previous time adjustment wouldn't complete"
bug on alpha when running NTP w/o the kernel PLL selected by "options
NTP".  It turned out to be an LP64 glitch, now fixed in
lib/libntp/systime.c

NTP now appears to behave itself a bit better on alpha both with and
without "options NTP". 

I suspect there are other LP64 glitches in there as well; rather than
hunting for them it might be more profitable to import xntp 4.x which
I believe already has a bunch of LP64 fixes in it..

I've submitted pullups to the 1.4 branch for all the necessary fixes,
since they're relatively localized.

					- Bill