RFR (S) cleanup misc issues prior to Contended Locking reorder and cache line bucket (8047104)

[Daniel D. Daugherty]

Greetings,

I have the fix for the following bug ready for JDK9 RT_Baseline:

     JDK-8047104 cleanup misc issues prior to Contended Locking
                 reorder and cache line bucket
     https://bugs.openjdk.java.net/browse/JDK-8047104

Here is the URL for the webrev:

http://cr.openjdk.java.net/~dcubed/8047104-webrev/0-jdk9-hs-rt/

Summary of the cleanups:

- change Java Monitor related 'unstable' and 'unsafe' options from
   'product' to 'experimental'; experimental didn't exist back when
   these options were added to the VM
- delete os::PlatformEvent::TryPark(), SharedRuntime::_monitor_enter_ctr,
   and SharedRuntime::_monitor_exit_ctr
- add 'const' to some places
- tidy some variable decls/inits, rename some parameters to proper
   HotSpot style
- add some assert()s and guarantee()s
- add/correct/update comments

Testing:

- JPRT test job
- Aurora AdHoc vm.quick with Server VM fastdebug bits on all the
   usual platforms is in process

Thanks, in advance, for any comments, questions or suggestions.

Dan