setup.sh: link: fix issue creating unnecessary symlinks

As of now the link function follows the destination path if already
existent and then creates a new symlink in there. In order to not create
this unnecessary additional symlink a check has been added which simply
checks if a symlink already exists in order to delete it.

setup.sh

@@ -13,17 +13,23 @@ link()
 	local src="$(pwd)/$1"
 	local dst="$2"
 
-	if test -e "$dst" && ! test -L "$dst"; then
-		echo "File $dst exists and is no symlink.\nIgnore and continue? (y/N)"
-		read answer
-		case $answer in
-			[Yy]*)
-				return
-				;;
-			*)
-				exit 1
-				;;
-		esac
+	if test -e "$dst"; then
+		if ! test -L "$dst"; then
+			echo "File $dst exists and is no symlink."
+			echo "Ignore and continue? (y/N)"
+			read answer
+			case $answer in
+				[Yy]*)
+					return
+					;;
+				*)
+					exit 1
+					;;
+			esac
+		else
+			# symlink already exists and will be removed
+			rm "$dst"
+		fi
 	fi
 
 	if installed printf; then