Make sure separated_poh_p and use_large_pages_p works together

[cshung]

This fixes 3 issues in the area:

1. If we decided to give some memory to POH even when it is set to 0, we should adjust the corresponding heap_hard_limit and heap_hard_limit_oh to avoid failing the virtual_commit call. The virtual_commit call consumes the heap_hard_limit regardless of whether or not the memory is actually committed.

2. In the large page case, if we decided to allocate the POH part of the memory using normal pages, then we need to commit them as well because the rest of the system assumes all the memory of large page cases is committed upfront.

3. virtual_free could be called by reserve_initial_memory if the memory operations fail, therefore it could be called in the heap_hard_limit case as well, removing the erroneous assert in that case.

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Issue Details

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Author:	cshung
Assignees:	-
Labels:	area-GC-coreclr
Milestone:	-

[ghost]

Tagging subscribers to this area: @dotnet/gc
See info in area-owners.md if you want to be subscribed.

Issue Details

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Author:	cshung
Assignees:	-
Labels:	area-GC-coreclr
Milestone:	-

[Maoni0]

LGTM!