RFR: 8345656: Move os alignment functions out of ReservedSpace [v2]

[Stefan Karlsson]

> I have a wish to simplify the ReservedSpace classes (See: [JDK-8345655](https://bugs.openjdk.org/browse/JDK-8345655)) and as a small step I would like to move the small helper functions that align addresses and sizes to `os::vm_page_size()` and `os::vm_allocation_granularity()` out to be `os::` helpers.
> 
> Tested tier1-3 together with the other patches in the JDK-8345655 prototype.

Stefan Karlsson has updated the pull request incrementally with one additional commit since the last revision:

  Copyright

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22600/files
  - new: https://git.openjdk.org/jdk/pull/22600/files/326f32f7..2da8bade

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22600&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22600&range=00-01

  Stats: 4 lines in 4 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/22600.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22600/head:pull/22600

PR: https://git.openjdk.org/jdk/pull/22600