[RFR] Instrumentation for basic Unsafe put/get

[Arthur Eubanks]

Forgot to mention:
This does slow down usage of Unsafe in the interpreter when the TSAN
feature is enabled at compile time, but since the interpreter is so slow,
it doesn't matter anyway. C1/C2 have their own implementation of Unsafe, so
those should not be affected.

On Tue, Sep 17, 2019 at 9:34 AM Arthur Eubanks <aeubanks at google.com> wrote:

> webrev:
> http://cr.openjdk.java.net/~aeubanks/tsannormalunsafe/webrev.00/index.html
>
> This change adds instrumentation for the interpreter Unsafe
> implementation, only for Unsafe_{Get,Put}{Reference,primitive}. Other
> Unsafe instrumentation will come later.
>