add rpm generation code

src/preremove.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+if command -v systemctl >/dev/null 2>&1; then
+    if [ "$1" -eq 0 ]; then
+        systemctl stop vctp.service || :
+        systemctl disable vctp.service || :
+    fi
+fi