build: make some noise on stale PID

This should be fixed in ports now, but let's not gamble too much.

build/common.sh

@@ -865,7 +865,7 @@ ${PLUGINSDIR}
 	if [ -d ${STAGE}/var/run ]; then
 		PIDS=$(find ${STAGE}/var/run -name "*.pid")
 		for PID in ${PIDS}; do
-			pkill -F ${PID} || true;
+			pkill -F ${PID} || echo ">>> Stale PID file ${PID}";
 		done
 	fi