Fix top level make clean

Makefile

@@ -39,22 +39,10 @@ shell:
 	docker run -it -v $$PWD:$$PWD --workdir $$PWD rayburgemeestre/build-ubuntu:18.04 /bin/bash
 
 clean:
-	make -C allegro5 clean
-	#make -C apt-publisher clean
-	make -C benchmarklib clean
-	make -C opentelemetry-cpp clean
-	make -C boost clean
-	make -C redis-plus-plus clean
-	make -C caf clean
-	make -C crtmpserver clean
-	make -C openexr clean
-	make -C fastpfor clean
-	make -C ffmpeg clean
-	make -C mesa clean
-	make -C png++ clean
-	make -C seasocks clean
-	make -C sfml clean
-	make -C v8pp clean
-	make -C fmt clean
+	for dir in */; do \
+		if [ -f "$$dir/Makefile" ]; then \
+			make -C $$dir clean; \
+		fi \
+	done