This introduces VMAddressSpace::FindClosestArea() that can be used to
find the closest area to a given address in either direction. This is
now trivial and efficient since both kernel and user address spaces use
a binary search tree.
Using FindClosestArea() getting multiple area infos is sped up
dramatically as it removes the need for a linear search from the first
area to the one given in the cookie on each successive invocation.
Change-Id: I227da87d915f6f3d3ef88bfeb6be5d4c97c3baaa
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2840
Reviewed-by: waddlesplash <waddlesplash@gmail.com>