RFR 8161444 VarHandles should provide access bitwise atomics

[Paul Sandoz]

Hi

Please review the following webrev which combines:

  8161444 VarHandles should provide access bitwise atomics
  8162107 Add acquire/release variants for getAndSet and getAndAdd

  http://cr.openjdk.java.net/~psandoz/jdk9/JDK-8161444-vhs-bitwise-atomics/webrev/
  http://cr.openjdk.java.net/~psandoz/jdk9/JDK-8161444-vhs-bitwise-atomics/specdiff/overview-summary.html

The set of access modes are expanded for support bitwise or/and/xor operations for volatile/acquire/release. Acquire/release getAndAdd and getAndSet access modes are also added (a future webrev will remove getAndAdd). This gets closer to parity with C++ atomics.

As a follow on i will:

- update the Hotspot Unsafe tests as a separate issue (the VarHandle tests implicitly test the Unsafe methods).

- log HotSpot bugs for making the Unsafe bitwise atomics intrinsic for various platforms.

Thanks,
Paul.