RFR: Fix Minimal VM build failures [v3]

[Alan Bateman]

On Tue, 28 Sep 2021 15:39:12 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Minimal VM configs have no C2 and no JVMTI. New Loom code fails the Minimal VM builds because of this. See for example GHA runs: https://github.com/shipilev/loom/runs/3717293969?check_suite_focus=true
>> 
>> C2 needs just a little bit of protection when reaching to `DerivedPointersTable`.
>> 
>> JVMTI needs a bit more work. `jvmtiExport` and `jvmtiThreadState` headers are usually included even with JVMTI turned off, but `.cpp` would not be compiled without JVMTI. Therefore, non-trivial implementations should go into `.cpp`. Plus, some of the paths that call the actual methods declared but not implemented without JVMTI should be protected with `INCLUDE_JVMTI`.
>> 
>> Additional testing:
>>  - [x] Linux x86_64 server, `tier1_loom` still passes (includes JVMTI tests)
>>  - [x] Linux x86_64 minimal now builds, runs `tier1_loom` (cannot pass JVMTI tests without JVMTI)
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   INCLUDE_JVMTI all Thread methods

The latest comment (9ba55ed) looks fine.

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PR: https://git.openjdk.java.net/loom/pull/67