RFR [9] 2018-03-26: Bulk backports to sh/jdk9

[Aleksey Shipilev]

This backports last week's work to sh/jdk9:

[backport] Remove narrowOop variants of oopDesc::equals and related methods
[backport] Keep track of per-cycle mutator/collector allocs. Fix mutator/collector alloc region
overlap in traversal.
[backport] Rename and cleanup _regions and _free_set uses
[backport] Full GC should not trash empty regions

Testing: hotspot_gc_shenandoah {fastdebug|release}

Thanks,
-Aleksey