RFR(s): 8214180: Need better granularity for sleeping

[Robbin Ehn]

Hi all, please review.

naked_short_sleep is to coarse grained on contemporary hardware/os:es.
1 ms as minimum when we can complete an entire safe-point in 0.5 ms is a very 
long time.
Sleeping a very short time instead yielding have several uses-cases.

Here I add it SpinYield to get much smother back-off delay curve.
Which means it will be usable in more places.

CR:
https://bugs.openjdk.java.net/browse/JDK-8214180

Webrev:
http://cr.openjdk.java.net/~rehn/8214180/webrev/

Passes t1-3.

Thanks, Robbin