RFR [8u]: Bulk backport to sh/jdk8u

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk8u-20171026/webrev.01/

This bugfix bunch comes with compiler fixes by Roland mostly.

The changes include:

rev 10155 : [backport] Rewrite and fix ShenandoahHeap::marked_object_iterate
rev 10156 : [backport] barrier moved due to null checks needs to always fix memory edges
rev 10157 : [backport] Incorrect constant folding with final field and -ShenandoahOptimizeFinals
rev 10158 : [backport] AESCrypt.implEncryptBlock/AESCrypt.implDecryptBlock intrinsics assume non
null inputs
rev 10159 : [backport] keep read barriers for final instance/stable field accesses
rev 10160 : [backport] Added diagnostic flag ShenandoahOOMDuringEvacALot
rev 10161 : [backport] Rename dynamic heuristics to static
rev 10162 : [backport] Static heuristics should use non-zero allocation threshold
rev 10163 : [backport] Static heuristics should be really static and report decisions

Testing: hotspot_gc_shenandoah {fastdebug|release}

Thanks,
-Aleksey