Fix permissions in package, don't change it in postinst

debian/postinst

                $SERVER_USER
 
        chown $SERVER_USER: $SERVER_HOME $SERVER_LOG
-       chmod u=rwx,g=rx,o= $SERVER_HOME
-       chmod u=rwx,g=rx,o=rx $SERVER_LOG
     ;;
 
     abort-*)

debian/rules

 override_dh_auto_clean:
 	dh_auto_clean
 	rm -f src/modules.c
+
+override_dh_fixperms:
+	dh_fixperms
+	chmod 750 $(CURDIR)/debian/rspamd/var/lib/rspamd