Fix FlxPointer.overlaps with different cameras

[Starmapo]

This fixes pointer overlaps when using a camera that isn't the global one.
Currently, it uses the pointer's position in the global camera (getPosition), which won't work properly when using another one unless its properties are the exact same.

Code to reproduce this issue:

import flixel.FlxCamera;
import flixel.FlxG;
import flixel.FlxSprite;
import flixel.FlxState;
import flixel.text.FlxText;

class PlayState extends FlxState
{
	var hudCamera:FlxCamera;
	var spr:FlxSprite;
	var text:FlxText;

	override public function create()
	{
		hudCamera = new FlxCamera(0, 0, Std.int(FlxG.width * 0.25), Std.int(FlxG.height * 0.25));
		hudCamera.setPosition(FlxG.width - hudCamera.width, FlxG.height - hudCamera.height);
		hudCamera.bgColor = flixel.util.FlxColor.GRAY;
		FlxG.cameras.add(hudCamera, false);

		add(spr = new FlxSprite());
		spr.cameras = [hudCamera];

		add(text = new FlxText(5, 5, FlxG.width - 10, '', 16));

		super.create();
	}

	override public function update(elapsed:Float)
	{
		super.update(elapsed);

		text.text = FlxG.mouse.overlaps(spr, hudCamera) ? "Overlapping" : "Not overlapping";
	}
}

[Geokureli]

thanks!