RFR: Fix Minimal VM build failures [v2]

[Chris Plummer]

On Tue, 28 Sep 2021 06:33:43 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:
> 
>   Cleaner disabling

src/hotspot/share/runtime/thread.hpp line 1268:

> 1266:     return false;
> 1267: #endif
> 1268:   }

If you #ifdef out the API, then you know it's not being called, thus no need for #else sections and calls to `fatal()`.

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