RFR(M): 8156923: [ppc] Implement "JEP 270: Reserved Stack Areas for Critical Sections".

[Lindenmaier, Goetz]

Hi,

This change ports JEP 270 to ppc.

It adapts the corresponding test to run also on ppc. Further I enabled test cases
for the interpreter and dedicated C1/C2, which helped me to find some initial
problems.
The change does not affect the behavior of any other platform.

Please review this change. I please need a sponsor.
http://cr.openjdk.java.net/~goetz/wr16/8156923-resStack/webrev.01/

Best regards,
  Goetz.