GB: Problem polling gamepad inputs?

[Screwtapello]

While exploring the GB emulation core, @asuramaru discovered what is almost certainly a copy/paste error in the code:

https://github.com/higan-emu/higan/blob/1b8c21499f15ff492665fd012ac77ad9436c4dc6/higan/gb/system/controls.cpp#L31-L37

It would be easy enough to just change that last downLatch to rightLatch, but I'd like to double-check the equivalent code in (say) Same Boy and mGBA and maybe look it up in one of the seventeen Pan Docs variants, just to be sure.