Avoid recommitting the mark array

[cshung]

This change fixes #75207.

When we init_heap_segment, we preserve the heap_segment_flags_ma_committed, and before we commit_mark_array_new_seg, we check the flag first and avoid recommitting.

For reviewers, I assumed (i.e. please check):

• The place I changed in the only call site where we commit for the mark array for regions. The other ones are either not defined under USE_REGIONS, or it is for frozen segments where by design it can never overlap with the region reserved range, and
• Since frozen segments can never overlap with the reserved range, we should never have a region (or a frozen segment) with the flag heap_segment_flags_ma_pcommitted turned on under USE_REGIONS.

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Issue Details

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This change fixes #75207.

When we init_heap_segment, we preserve the heap_segment_flags_ma_committed, and before we commit_mark_array_new_seg, we check the flag first and avoid recommitting.

For reviewers, I assumed (i.e. please check):

• The place I changed in the only call site where we commit for the mark array for regions. The other ones are either not defined under USE_REGIONS, or it is for frozen segments where by design it can never overlap with the region reserved range, and
• Since frozen segments can never overlap with the reserved range, we should never have a region (or a frozen segment) with the flag heap_segment_flags_ma_pcommitted turned on under USE_REGIONS.

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