ntdll: Introduce a new subheap thread affinity field.
To associate a subheap with a specific thread that will be its only user. Other threads may only defer the block free of subheap with a different affinity, through locking and defer list.
To associate a subheap with a specific thread that will be its only user. Other threads may only defer the block free of subheap with a different affinity, through locking and defer list.