The CGEvent implementation for scroll wheel events isn't correct for ARM64

[rolfbjarne]

Current implementation:

xamarin-macios/src/CoreGraphics/CGEvent.cs

Lines 112 to 131 in c65bdc7

	public CGEvent (CGEventSource source, CGScrollEventUnit units, params int [] wheel)
	{
	IntPtr shandle = source == null ? IntPtr.Zero : source.Handle;
	switch (wheel.Length){
	case 0:
	throw new ArgumentException ("At least one wheel must be provided");
	case 1:
	handle = CGEventCreateScrollWheelEvent (shandle, units, 1, wheel [0]);
	break;
	case 2:
	handle = CGEventCreateScrollWheelEvent (shandle, units, 2, wheel [0], wheel [1]);
	break;
	case 3:
	handle = CGEventCreateScrollWheelEvent (shandle, units, 3, wheel [0], wheel [1], wheel [2]);
	break;
	default:
	throw new ArgumentException ("Only one to three wheels are supported on this constructor");
	}
	}

This needs to take into account that varargs parameters aren't in the same place on ARM64.

Example:

xamarin-macios/src/CoreGraphics/CGColorConversionInfo.cs

Lines 94 to 105 in c65bdc7

	if (Runtime.IsARM64CallingConvention) {
	Handle = CGColorConversionInfoCreateFromList_arm64 (o, first.Space.GetHandle (), (uint) first.Transform, (int) first.Intent,
	IntPtr.Zero, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero,
	second.Space.GetHandle (), (uint) second.Transform, (int) second.Intent,
	third.Space.GetHandle (), (uint) third.Transform, (int) third.Intent,
	IntPtr.Zero);
	} else {
	Handle = CGColorConversionInfoCreateFromList (o, first.Space.GetHandle (), first.Transform, first.Intent,
	second.Space.GetHandle (), second.Transform, second.Intent,
	third.Space.GetHandle (), third.Transform, third.Intent,
	IntPtr.Zero);
	}

Also we need tests for this.