RFR [9]: Bulk backport to sh/jdk9

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk9-20171025/webrev.01/

Changes include:

rev 13698 : [backport] Rewrite and fix ShenandoahHeap::marked_object_iterate
rev 13699 : [backport] Eliminate string dedup cleanup phase and correct UR closure
rev 13700 : [backport] barrier moved due to null checks needs to always fix memory edges
rev 13701 : [backport] Incorrect constant folding with final field and -ShenandoahOptimizeFinals
rev 13702 : [backport] AESCrypt.implEncryptBlock/AESCrypt.implDecryptBlock intrinsics assume non
null inputs
rev 13703 : [backport] keep read barriers for final instance/stable field accesses
rev 13704 : [backport] Added diagnostic flag ShenandoahOOMDuringEvacALot
rev 13705 : [backport] Rename dynamic heuristics to static
rev 13706 : [backport] Static heuristics should use non-zero allocation threshold
rev 13707 : [backport] Static heuristics should be really static and report decisions
rev 13708 : [backport] missing must_be_not_null() for arguments to String compareTo*/equals*

These are mostly compiler fixes, so I would like Roland to take a hard look on these. Zhengyu, we
are backporting String dedup fix, even though it still fails the string dedup stress intermittently.
Roman, take at the remaining parts too?

Testing: hotspot_gc_shenandoah {fastdebug|release}

Thanks,
-Aleksey