Solved a bunch of -Wall errors on modern

src/field_effect_helpers.c

@@ -1658,7 +1658,7 @@ static void UpdateGrassFieldEffectSubpriority(struct Sprite *sprite, u8 elevatio
 {
     u8 i;
     s16 var, xhi, lyhi, yhi, ylo;
-    const struct ObjectEventGraphicsInfo *graphicsInfo; // Unused Variable
+    const struct ObjectEventGraphicsInfo UNUSED *graphicsInfo;
     struct Sprite *linkedSprite;
 
     SetObjectSubpriorityByElevation(elevation, sprite, subpriority);