Msvc/Arm: Pass /D_ARM_WINAPI_PARTITION_DESKTOP_SDK_AVAILABLE=1 to cl.exe

[jordanrh1]

This flag must be defined to avoid a compilation error.

[alexcrichton]

Thanks! Is there perhaps some documentation we could point to to say why we're passing this flag?

[jordanrh1]

The documentation is the source code :) From corecrt.h:

// Verify that the ARM Desktop SDK is available when building an ARM Desktop app
#ifdef _M_ARM
    #if _CRT_BUILD_DESKTOP_APP && !_ARM_WINAPI_PARTITION_DESKTOP_SDK_AVAILABLE
        #error Compiling Desktop applications for the ARM platform is not supported.
    #endif
#endif

The check was added in Windows 8 days because only store apps were allowed on ARM, but this changed with the release of Windows 10 IoT Core. This check will be going away in future versions of the SDK, but for all released versions of the Windows SDK it is required.

[alexcrichton]

Ok cool! Could you add that all in a comment next to the source here?

[jordanrh1]

Sure, done.

[alexcrichton]

Thanks!