[rt46602] More updates to the test running framework

Tidy up the stop/start files and make switch usage consistent. Also
tidy up the various "clean" targets in the Makefile.

bin/tests/system/Makefile.in

@@ -75,13 +75,20 @@ test: parallel.mk
 
 check: test
 
-# Other targets.
+# Other targets:
+#
+# testclean - delete files generated by running tests
+# clean - As for testclean, but also delete files built for the tests by "make"
+# distclean - As for clean, but also delete test-related files generated by
+#        "configure"
 
 testclean clean distclean::
 	if test -f ./cleanall.sh; then $(SHELL) ./cleanall.sh; fi
 	rm -f systests.output
 	rm -f random.data
 	rm -f parallel.mk
+
+clean distclean::
 	rm -f ${TARGETS}
 	rm -f ${OBJS}