Use pctrie iterators to walk a series of ranges in pmap_same testing for amd64 and arm64For rangeset-next search, use exact search rather than greater-than search.
For rangesets, searching with an iterator and an upper limit on search slightly optimizes the empty-ranges case. Searching for the next exact match, rather than for the next greater-than-or-equal-to match, and using an iterator, slightly optimizes the range-fully-packed case.
These changes depend on the pctrie changes in [D45627]Move a bit of the testing logic from the pmap code to the rangeset code.