[RuntimeAsync] PGO support for async methods

[VSadov]

Currently we have the following TODO:

    // TODO: (async) PGO support for async variants
    if (pMD->IsAsyncVariantMethod())
        return false;

PGO is disabled for async callconv methods. While not critical, it would make sense to enable.

I am going to remove the TODO.
Let's use this issue to track the workitem.

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[jakobbotsch]

I assume you mean the occurrence in ReadyToRunInfo::GetPgoInstrumentationData.
If this is only PGO information for R2R functions then it is not as critical, but still needs to be looked at.

Do you remember why this TODO was needed in the first place? What was the issue? We did the work to make PGO work for regular tiered methods from the beginning, so hopefully this would not need much additional work.

[VSadov]

I think the part

if (pMD->IsAsyncVariantMethod())
        return false;

goes all the way back to the beginning of the experiment. I guess PGO support was not the first priority and was preventatively turned off to not be a distraction. The TODO was added later to not forget to come back.
I am not sure how much work remains/needed to un-disable this for async methods. Maybe it just works or almost works.

I am going to remove the TODO though as I think this is not blocking for enablement of async feature. Having a follow up issue (this one) is enough to make sure this will be dealt with eventually.