RFR(S): 8147844: new method j.l.Runtime.onSpinWait() and the corresponding x86 hotspot instrinsic

[Ivan Krylov]

I have prepared a new webrev:
http://cr.openjdk.java.net/~ikrylov/8147844.hs.02/

Hopefully it addresses the comments that were said before.
Per Vladimir's suggestion I added the c1 intrinsic.
I could not test non-x86 platforms but hopefully nothing is broken there.

Thanks,

Ivan