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

[Magnus Ihse Bursie]

On Thu, 15 Oct 2020 18:35:30 GMT, Bernhard Urban-Forster <burban at openjdk.org> wrote:

>> 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

Build changes look fine now.

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Marked as reviewed by ihse (Reviewer).

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