timecounting: use C99-style initialization for all timecounter structs

timecounting: use C99-style initialization for all timecounter structs

The timecounter struct is large and I think it may change in the
future.  Changing it later will be easier if we use C99-style
initialization for all timecounter structs.  It also makes reading the
code a bit easier.

For reasons I cannot explain, switching to C99-style initialization
sometimes changes the hash of the resulting object file, even though
the resulting struct should be the same.  So there is a binary change
here, but only sometimes.  No behavior should change in either case.

I can't compile-test this everywhere but I have been staring at the
diff for days now and I'm relatively confident this will not break
compilation.  Fingers crossed.

ok gnezdo@