Add Windows ARM64 support in CI

[Harishmcw]

This PR adds Windows ARM64 support to the MSBuild and CMake CI workflows.

Changes:

• CMake
  • Added Windows-MSVC-ARM64 and Windows-MinGW-ARM64 jobs.
  • Configured appropriate vcpkg triplets and generators.
  • Added conditional -A handling for MSVC ARM64 builds.
• MSBuild
  • Added ARM64 platform configuration to portaudio.vcproj and portaudio.sln
  • Added ARM64 to the CI build matrix.

[RossBencina]

To check that this wasn't going to create backward compatibility problems I opened the .sln solution in Visual Studio 2005. There were no obvious problems introduced by the presence of the ARM64 configuration (it would not build of course). The Win32 target seemed to build (modulo some unrelated errors that we should probably fix).

Could I get you to fix one more thing please? : When I opened the solution ARM64 was already the selected configuration. Could you make open with the 64-bit intel config please?

[Harishmcw]

Hi @RossBencina,

After some investigation I found that on Visual Studio 2005, the default configuration is picked alphabetically, since ARM64 sorts before x64, it ends up selected by default.

[RossBencina]

@Harishmcw thanks for looking into it. We're intending to merge this as-is but could you please provide us with a short explanation of how you made the changes to the .vcproj file? Have you tested it locally? I don't have the ARM toolchain installed here. I can confirm that the .vcproj does load and convert in VS2022 with a warning about no ARM toolchain (see below) not a problem, just commenting for completeness. Interestingly VS2022 then selects the x64 configuration non-alphabetically even though there is a Win32 configuration.

[RossBencina]

Approved, but let's finish the conversation first. I would like to know how you generated the .vcproj changes, including which VisualStudio version you used, and whether you tested it locally. We may include some of these details in the commit message.

[Harishmcw]

The .vcproj changes were made manually by cloning the existing x64 configuration blocks, adding _ARM64 to preprocessor definitions, and updating output filenames. The updated .vcproj was upgraded to .vcxproj using Visual Studio 2022 and built successfully for ARM64 locally, producing portaudio_arm64.dll.