RFR: 8254072: AArch64: Get rid of --disable-warnings-as-errors on Windows+ARM64 build [v4]

[Bernhard Urban-Forster]

> I organized this PR so that each commit contains the warning emitted by MSVC as commit message and its relevant fix.
> 
> Verified on
> * Linux+ARM64: `{hotspot,jdk,langtools}:tier1`, no failures.
> * Windows+ARM64: `{hotspot,jdk,langtools}:tier1`, no (new) failures.
> * internal macOS+ARM64 port: build without `--disable-warnings-as-errors` still works. Just mentioning this here, because
>   it's yet another toolchain (Xcode / clang) that needs to be kept happy [going
>   forward](https://openjdk.java.net/jeps/391).

Bernhard Urban-Forster has updated the pull request incrementally with two additional commits since the last revision:

 - uppercase suffix
 - add assert

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/530/files
  - new: https://git.openjdk.java.net/jdk/pull/530/files/32e922da..901bbd48

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=530&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=530&range=02-03

  Stats: 2 lines in 2 files changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/530.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/530/head:pull/530

PR: https://git.openjdk.java.net/jdk/pull/530