Very unfortunate that this has to go into the overlay translation unit
due to the upcoming functions near-calling the `far overlay_wipe()`
function.
Part of P0279, funded by Yanga and Blue Bolt.
These functions are placed rather far away from other stage-related
code, which suggests a distinct translation unit.
Part of P0245, funded by [Anonymous], Blue Bolt, Ember2528, and Yanga.
By leaving out just the one `score_delta = 0;` assignment, ZUN created
a function with semantics so complex that it already required naming
all other score-related functions just to make sense of it.
Part of P0242, funded by Yanga.
nmlgc