Enable warnings as errors on Aarch64 in the JIT

[dylanjtuttle]

"Warnings as errors" is enabled on a component-by-component basis throughout OpenJ9 and OMR. For the JIT, warnings as errors is enabled on every platform in OMR and on x86 and Z in OpenJ9.

This PR enables warnings as errors on Aarch64 in OpenJ9 by:

• Turning the OMR_WARNINGS_AS_ERRORS flag on if OMR_ARCH_AARCH64 is true
• Removing the --disable-warnings-as-errors flag which is passed into Aarch64 Mac builds on Jenkins by default

This will ensure all builds on Aarch64 compile code with the -Werror flag, which will halt compilation if a warning is reported.

[dylanjtuttle]

@0xdaryl as we discussed earlier today...

[0xdaryl]

@knn-k : any objections to enabling this now?

[knn-k]

No objection.
I built AArch64 OpenJ9 JDK 17 for Linux and macOS locally, and both of them were OK with warnings-as-errors.

[knn-k]

Build jobs at internal servers finished successfully:

• job/Build_JDK17_aarch64_linux_Personal/461/ (Linux)
• job/Build_JDK17_aarch64_mac_Personal/193/ (macOS)

[0xdaryl]

There are no community build jobs to test this, but internal testing runs fine.

[pshipton]

There are no community build jobs to test this, but internal testing runs fine.

@0xdaryl are you referring to the UNB testing problems or something else? alinux isn't at UNB, and we can do builds at UNB, the main problem is running testing.

[0xdaryl]

Yes, I was referring to the UNB problems. My mistake about alinux.

Konno-san tested this internally on a couple of configurations before we merged this so I don't think we'll see any problems.

[pshipton]

I wasn't concerned, I just wanted you to be aware that we can build JVMs at UNB even if we can't test them all concurrently (we can run a limited amount of testing).