Codechange: address CodeQL issue "Multiplication result converted to larger type" (#10306)

Most are very unlikely to ever be triggered in our codebase; two
stand out: linkgraph and money cheat. Those, potentially, could
wrap earlier than expected.

src/fontcache/freetypefontcache.cpp

@@ -240,7 +240,7 @@ const Sprite *FreeTypeFontCache::InternalGetGlyph(GlyphID key, bool aa)
 
 	/* FreeType has rendered the glyph, now we allocate a sprite and copy the image into it */
 	SpriteLoader::Sprite sprite;
-	sprite.AllocateData(ZOOM_LVL_NORMAL, width * height);
+	sprite.AllocateData(ZOOM_LVL_NORMAL, static_cast<size_t>(width) * height);
 	sprite.type = ST_FONT;
 	sprite.colours = (aa ? SCC_PAL | SCC_ALPHA : SCC_PAL);
 	sprite.width = width;