[llvm] [orc-rt] Add Windows page size detection (PR #224520)

[Lang Hames via llvm-commits]

https://github.com/lhames approved this pull request.

Testcase changes probably conflict with my recent ones (sorry!), but otherwise LGTM. Good to land as soon as the conflicts are resolved.

https://github.com/llvm/llvm-project/pull/224520