update_config.sh: use vars

update_config.sh

 #!/bin/bash -e
 
+SRC=src/linux
+CONFIG=config.x86_64
+
 config_equal()
 {
-	diff -q -s src/linux/.config config.x86_64 &>/dev/null
+	diff -q -s "$SRC/.config" "$CONFIG" &>/dev/null
 }
 
 if config_equal; then
-	(cd src/linux && make menuconfig)
+	(cd "$SRC" && make menuconfig)
 else
-	[[ -e src ]] && rm -rf src
+	[[ -e "$SRC" ]] && rm -rf "$SRC"
 	makepkg --nobuild --force
-	(cd src/linux && make oldconfig)
+	(cd "$SRC" && make oldconfig)
 fi
 
 if ! config_equal; then
-	cp src/linux/.config config.x86_64
+	cp -v "$SRC/.config" "$CONFIG"
 	updpkgsums
 fi