[foreign-memaccess+abi] RFR: 8299911: Refactor struct handling in AArch64 CallArranger [v3]

[Jorn Vernee]

> Refactor struct handling in AArch64 CallArranger.
> 
> Instead of having 6 very similar looking while loops, I've consolidated the storage allocation code for structs into a single helper method (`StorageCalculator::structStorages`). This should make it much easier to see which logic is being used for a particular case.

Jorn Vernee has updated the pull request incrementally with two additional commits since the last revision:

 - Clarify comment, take 3
 - Clarify comment, take 2

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Changes:
  - all: https://git.openjdk.org/panama-foreign/pull/765/files
  - new: https://git.openjdk.org/panama-foreign/pull/765/files/b9680432..3ac117fd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=panama-foreign&pr=765&range=02
 - incr: https://webrevs.openjdk.org/?repo=panama-foreign&pr=765&range=01-02

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/765.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/765/head:pull/765

PR: https://git.openjdk.org/panama-foreign/pull/765