RFR: [9] Bulk backports to sh/jdk9

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk9-20180126/webrev.01/

Changes include:

8735773ec619: Single thread-local GC state flag for all barriers
544322604347: ShConcurrentThread races with set_gc_state_bit
dc779781dd5e: Do not put down update-refs-in-progress flag concurrently
d55c6d5216d1: Common TLS access to GC state, where possible
1d1238a0603b: Defer cleaning of system dictionary and friends to parallel cleaning phase
fd9724b26fdd: Refactor allocation failure and explicit GC handling
e5398dce6e7b: Make concurrent precleaning log message optional again
26b9048c042a: Make degenerated update-refs use region-set cursor to hand over work
1a6a9f288dd2: Bitmap size might not be page aligned when large page is used
12654193e434: Demote warning message about OOM-during-evac to informational
67294a38c0c7: TestSelectiveBarrierFlags should accept multi-element flag selections
ecb87af5e0d8: Implement flag to generate write-barriers without membars.
820129a799b1: Allocation failure injection machinery
b8c39bdc0dac: Log message on ref processing, class unload, update refs for mark events
45d471869b73: Degenerated GC
15261c4a6adf: Degenerated GC: shortcut cycles, upgrade futile cycles
bd01b07ba0d7: Add ShenandoahRootProcessor API to report threads while scanning roots
3a6457fecc72: Relax assert in SBS::is_safe()
30e8ba6e2794: VerifyJCStressTest should test all heuristics
6183a72bd5c2: ShBS::interpreter_storeval_barrier signature fix and cleanup
3c12448ec444: Fix 32-bit build by ifdef-ing non-implemented storeval barrier

Testing: hotspot_gc_shenandoah {fastdebug|release}, specjvm

Thanks,
-Aleksey