RFR [10]: 2018-04-03, Bulk backports to sh/jdk10

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk10-20180403/webrev.01/

This backports recent work to sh/jdk10:

8dbb27537ca8: [backport] Fixed missing ResourceMark in ShenandoahAsserts::print_obj
e13faea29f1e: [backport] Degenerated GC mode for Traversal
7afaf1af2f2d: [backport] Fix Windows build
232d819bc452: [backport] Shenandoah critical native support
6d6f2a740d08: [backport] UX: Shorter gc+ergo messages from CSet selection
74ecc8c9d1e4: [backport] UX: Pacer reports incorrect free size
b3da459bb972: [backport] UX: Cleanup (adaptive) CSet selection message
22aa6971592a: [backport] Compact heuristics should not shortcut on immediate garbage, but
aggressively compact
70711ace6be3: [backport] Cleanup SHH::should_start_normal_gc
6275c07a33ab: [backport] FreeSet and HeapRegion should have the reference to ShenandoahHeap
2b786ecc55ad: [backport] Refactor FreeSet rebuilding into the single source
7b09e2a2acf0: [backport] FreeSet should accept responsibility over trashed regions
d798cbed3f20: [backport] Drop distinction between immediate garbage and free in heuristics
1d80812eaa8a: [backport] Do not add non-allocatable regions to the freeset
2c0fa03aaa4b: [backport] Pacer should poll FreeSet to figure out actually available space
2416e01eb9b9: [backport] Remove FreeSet::add_region, inline into FreeSet::rebuild
b8c8efc020ca: [backport] Remove obsolete check in FreeSet::allocate


Testing: hotspot_gc_shenandoah {fastdebug|release}

Thanks,
-Aleksey