RFR: 8205559: Remove IN_CONCURRENT_ROOT Access decorator

[Kim Barrett]

Please review the removal of the IN_CONCURRENT_ROOT Access decorator.

All non-AS_RAW IN_NATIVE accesses will be treated as potentially
concurrent, and so will require barriers appropriate to the selected
collector.

Renumbered the Access decorators, eliminating gaps and mis-orderings
that had accrued from previous removals and renamings.

Fixed StringDedupTable::lookup usage of the Access API.  It was using
IN_CONCURRENT_ROOT incorrectly, and was not using AS_NO_KEEPALIVE
where it should have been.  There are other places where this class is
not using the Access API but should be, involving the _obj field of
StringDedupTableEntry; addressing those will be part of a future CR,
since currently only ZGC would fail because of these and ZGC does not
yet support string deduplication.

CR:
https://bugs.openjdk.java.net/browse/JDK-8205559

Webrev:
http://cr.openjdk.java.net/~kbarrett/8205559/open.00/

Testing:
Mach5 tier1,2,3, hs-tier4,5

Aurora perf testing for G1 and Parallel detected no performance regressions.