rAthena missing bound check in chclif_parse_moveCharSlot

rAthena is an open-source cross-platform massively multiplayer online role playing game (MMORPG) server. Versions prior to commit 0cc348b are missing a bound check in `chclif_parse_moveCharSlot` that can result in reading and writing out of bounds using input from the user. The problem has been fixed in commit 0cc348b.