RFR: 8318127: align_up has potential overflow [v6]

[Casper Norrbin]

> Hi everyone,
> 
> The `align_up` function contained code which could potentially overflow and produce an incorrect result. This PR adds an assert to check for such.
> 
> Additionally, two test case that previously caused an overflow have been updated to use the highest possible values that do not trigger an overflow.

Casper Norrbin has updated the pull request incrementally with one additional commit since the last revision:

  ifdef

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/20808/files
  - new: https://git.openjdk.org/jdk/pull/20808/files/be66c7c4..a62a898a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20808&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20808&range=04-05

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20808.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20808/head:pull/20808

PR: https://git.openjdk.org/jdk/pull/20808