RFR(L): 8193257: PPC64, s390 implementation for Thread-local handshakes

[Doerr, Martin]

Hi,

I've implemented Thread-local handshakes on PPC64 and s390.

We may improve it by using SIGTRAP-based polling on these 2 platforms in the future (which requires changes in shared code).
For now, I just implemented it like on the other platforms without further improvements.

Webrev is here:
http://cr.openjdk.java.net/~mdoerr/8193257_PPC64_s390_Thread-local_hs/webrev.00/

Please review.

Best regards,
Martin