Add missing files to make clean

At present, "make clean" will not remove the module-Makefile files for
non-top-level modules.  It also won't remove the generated config.h.
Correct those errors.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Makefile

@@ -64,8 +64,9 @@ ccan/%/info: ccan/%/_info
 	$(CC) $(CCAN_CFLAGS) -o $@ -x c $<
 
 clean: tools-clean
-	$(RM) `find * -name '*.o'` `find * -name '.depends'` `find * -name '*.a'`  `find * -name info` `find * -name '*.d'`
-	$(RM) inter-depends lib-depends test-depends ccan/*-Makefile
+	$(RM) `find * -name '*.o'` `find * -name '.depends'` `find * -name '*.a'`  `find * -name info` `find * -name '*.d'` `find ccan -name '*-Makefile'`
+	$(RM) config.h
+	$(RM) inter-depends lib-depends test-depends
 
 # Creates a dependency from the tests to the object files which it needs.
 inter-depends: $(ALL_DEPENDS) Makefile