Fix a CC deadlock in 129-ThreadGetId.

GC should consider a thread as "waiting for GC thread flip" or
"transitioning to runnable" only if its suspend count is 1.

See 31683379#7 for the deadlock scenario.

Bug: 31683379
Bug: 12687968
Test: test-art with CC and gcstress, N9 libartd boot, Ritz EAAC.
Change-Id: Icd2548bd6d9a4f8d7b54ed20150a4801af9e26a3