Add -Awarnings on tests for ignoring warning from xcrun

[Shunpoco]

Context

close #145543
Those two tests fail on MacOS because xcrun puts a warning on StdErr.
The warning is only shown when we put -Zverbose-internals flag to the compiler.

Change

I added -Awarnings to those two tests to ignore the warning, because

1. verbose output from 3rd party tools like xcrun are sometimes useful for debugging
2. the warning doesn't ask us to take any actions (it looks just info-level log, I'm not sure why xcrun decided to output the message as warning), so we can safely ignore it I think

[Shunpoco]

r? @jieyouxu

[jieyouxu]

To me, this seems like papering over the root problem that -Z verbose-internals seem to be ... confusing, in terms of what it is supposed to do. That is, I feel like showing more output from xcrun when -Z verbose-internals based on flag name verbatim seems like a very reasonable thing to do. But it looks like the root problem is we probably need different flags between -ZI-want-verbose-type-system-details versus -ZI-want-linker-output...

Based on at least #103428, I don't think allowing warnings here is the right thing to do.

[jieyouxu]

I don't quite have the bandwidth to look into this ATM, sorry.
r? @madsmtm

[madsmtm]

Sorry for the delay. I agree that this isn't the right thing to do, and I have filed #145847 to fix it by not tying xcrun verbosity to -Zverbose-internals.

Thanks for the initiative though @Shunpoco!