Fix case where people don't use ./unrealircd hot-patch but use something

like /home/xyz/unrealircd/unrealircd hot-patch instead. In other words,
if the current working directory is not the location of the unrealircd
script. Then calling ./unrealircd rehash, so the last step in the patching
process, would fail. Reported by k4be.
[skip ci]

unrealircd.in

@@ -256,7 +256,7 @@ elif [ "$1" = "hot-patch" -o "$1" = "cold-patch" ] ; then
 	make || gmake || exit 1
 	make install || gmake install || exit 1
 
-	cd -
+	cd @SCRIPTDIR@
 	if [ "$1" = "hot-patch" ]; then
 		echo "Patch applied successfully and installed. Rehashing your IRCd..."
 		./unrealircd rehash