properly clean .d files

And also, _only_ clean our own files, not both a hard list of all files,
just the ones we built ourselves

examples/rules.mk

@@ -210,7 +210,7 @@ print-%:
 
 clean:
 	@#printf "  CLEAN\n"
-	$(Q)$(RM) *.o *.d *.elf *.bin *.hex *.srec *.list *.map generated.* ${OBJS} ${OBJS:%.o:%.d}
+	$(Q)$(RM) $(BINARY).{elf,bin,hex,srec,list,map} *.map generated.* $(OBJS) $(OBJS:%.o=%.d)
 
 stylecheck: $(STYLECHECKFILES:=.stylecheck)
 styleclean: $(STYLECHECKFILES:=.styleclean)