ARM64 support

[MichaelGrafnetter]

Hello, I noticed this code in CMakeLists.txt:

# 64-bit symbols for Visual Studio C++
if("${CMAKE_GENERATOR}" MATCHES "Visual Studio")
    if("${CMAKE_GENERATOR_PLATFORM}" MATCHES "x64")
        message(STATUS "NOTE: Setting 64-bit symbols")
        add_compile_definitions(
            _AMD64_
            _AMD64_SIMULATOR_
            _AMD64_SIMULATOR_PERF_
            _AMD64_WORKAROUND_
            _SKIP_IF_SIMULATOR_
            _WIN64
            AMD64
        )
    elseif("${CMAKE_GENERATOR_PLATFORM}" MATCHES "Win32")
        message(STATUS "NOTE: Setting 32-bit symbols")
        add_compile_definitions(
            _X86_=1
            FPO=0
            i386=1
            STD_CALL
        )
    else()
        message(FATAL_ERROR "NOTE: NOT setting 64-bit OR 32-bit symbols")
    endif()
else()
    message(FATAL_ERROR "NOTE: NOT setting 64-bit OR 32-bit symbols")

It seems that while x86 and x64 are supported, native ARM64 support is missing, e.g., Microsoft Surface Laptop Copilot+ with Snapdragon X.
It would also be nice if it did not end with a FATAL_ERROR for other cmake generators than Visual Studio. Defaulting to x64 would be nice.