StoatSpriteEngine: Clear cached font_size struct in SP_SetTextSpriteType

This fixes a bug where the wrong font was used on the Rance Quest status
screen.

Commit 6c2a55c reset `font_size` on size changes, but the same is needed
for face changes.

src/hll/StoatSpriteEngine.c

@@ -127,6 +127,8 @@ bool StoatSpriteEngine_SP_SetTextSprite(int sp_no, struct string *text)
 
 void StoatSpriteEngine_SP_SetTextSpriteType(int type)
 {
+	if (text_sprite_ts.face != type)
+		text_sprite_ts.font_size = NULL;
 	text_sprite_ts.face = type;
 }