RFR: JDK-8167659: Access of mark word should use oopDesc::mark_offset_in_bytes() instead of '0'

[Roman Kennke]

I posted this before:

http://mail.openjdk.java.net/pipermail/hotspot-dev/2016-October/024889.html

And just realized it's not been fixed yet. Maybe now would be a good
time to include it?

I believe this changeset address all the issues mentioned in the above
discussions.

http://cr.openjdk.java.net/~rkennke/8167659/webrev.00/
<http://cr.openjdk.java.net/%7Erkennke/8167659/webrev.00/>

Testing: jcstress -m sanity, specjvm
(cannot currently run jtreg tests because I've no idea how to run the
jcstress-jtreg tests..)

Roman