RFR (S) CR 8014964: @Contended breaks has_nonstatic_fields invariant

[Aleksey Shipilev]

Hi,

This is the fix for another issue found during the review:
   http://cr.openjdk.java.net/~shade/8014964/webrev.01/

This is the minimal fix which brings has_nonstatic_fields in order. The
whole method needs refactoring anyway to untangle *_count mess. I would
nevertheless commit this minimal fix to solve the immediate problem
while I'm working on further cleanups.

Testing:
  - adhoc Linux x86_64/fastdebug test/runtime/contended tests
  - full JPRT cycle against hotspot-rt is running now

Thanks,
-Aleksey.