RFR [10]: 2018-04-09, Bulk backports to sh/jdk10

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk10-20180409/webrev.01/

Includes:

88c7dab55e27: [backport] Adapt upstream object pinning API
ffc4775aa1da: [backport] Remove CSetThreshold handling from heuristics
71f1028fed44: [backport] Pacer should account allocation waste and unsuccessful pacing in the budget
bf6915a4b6a6: [backport] Hide is_concurrent_traversal_in_progress check under the type check
889aec72fd97: [backport] Move ShHeap::used increment out of locked allocation path
2dc4c4d5a9c8: [backport] Avoid notifying about zero waste

Testing: hotspot_gc_shenandoah {fastdebug|release}

Thanks,
-Aleksey