[NativeAOT] Use native Arm64 toolset on Windows Arm64 machines

[jkotas]

Fixes #76079

[Copilot]

Pull Request Overview

This PR changes the logic in findvcvarsall.bat to use the native Arm64 toolset on Windows Arm64 machines by updating how the vcEnvironment variable is set based on the processor architecture.

• Removed old processor architecture checks using PROCESSOR_ARCHITEW6432
• Added a new conditional block to differentiate between ARM64 and non-ARM64 machines
• Adjusted vcEnvironment values for parameters "x64", "x86", and "arm64" accordingly

Comments suppressed due to low confidence (1)

src/coreclr/nativeaot/BuildIntegration/findvcvarsall.bat:23

• [nitpick] Consider adding a comment explaining why the script now solely relies on PROCESSOR_ARCHITECTURE for detecting ARM64 machines, and how this change aligns with the removal of the previous PROCESSOR_ARCHITEW6432 check.

IF /I "%PROCESSOR_ARCHITECTURE%" == "ARM64" (

[jkotas]

I have verified on Win Arm64 machine that the change works as expected:

Before:

Task Parameter:Command="C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\bin\Hostx86\arm64\link.exe" @"obj\Release\net9.0\win-arm64\native\link.rsp" (TaskId:152)

After:

Task Parameter:Command="C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.44.35207\bin\Hostarm64\arm64\link.exe" @"obj\Release\net9.0\win-arm64\native\link.rsp" (TaskId:152)

[MichalStrehovsky]

Thanks!