Fix vertical aim being off when using lack of perspective

When using lack of perspective in OpenGL, the vertical aiming was off due when using a resolution that is not in the 16:10 aspect ratio. This is notable on ringslinger: if it's higher than 16:10, shots would be below the aim reticle and if it's lower than 16:10, it would be above the reticle (higher vertical aim would exaggregate the offset).

This patch fixes this by correcting the vertical aim using the aspect ratio, causing vertical aim to match the actual vertical look.