RFR (M) #2 CR 8003985: Support @Contended annotation

[Aleksey Shipilev]

Hi,

This is the revamp of JEP-142 aka @Contended, taking into the account
the feedbacks of Christian, Coleen and others:
  http://shipilev.net/pub/jdk/hotspot/contended/webrev-5/

The bottom line for most of the changes is dealing with footprint. I
think I've managed to squeeze into the same footprint by reusing
InstanceKlass::misc_flags to store class-level flag, and tagged field in
FieldInfo (as the side effect, cleaning up the mess with "temporarily
store type into offset field") to store per-field info.

Testing:
  - built and tested on Linux x86_64
  - Test8003985 is passing on Linux x86_64

Please take a look while I'm getting this through acceptance checks on
other platforms.

-Aleksey