RFR: 8271939: Clean up primitive raw accessors in oopDesc

[Aleksey Shipilev]

On Thu, 5 Aug 2021 11:20:58 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> We have some _raw accessors in oop.hpp and related code. Those are leftover from when Shenandoah required primitive barriers and are no longer needed. Their uses can be replaced with the regular accessors.
> 
> Testing:
>  - [x] tier1
>  - [x] tier2
>  - [x] hotspot_gc

Looking at the [RFE](http://hg.openjdk.java.net/jdk/jdk/rev/7c3891b9f1e0) that introduced these, I think `loader_data_raw` is also the candidate for removal?

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PR: https://git.openjdk.java.net/jdk/pull/5017