Don't delete *.bin files on 'make clean' - 'make distclean' does this

Makefile

@@ -61,6 +61,10 @@ $(SUBDIRS):
 	$(MAKE) -C $@
 
 clean:
+	-rm -f html_data.c html_data.h $(VERSION_HEADER)
+	-if [ -d $(BUILDDIR) ]; then find $(BUILDDIR) -type f ! -name "*.bin" -delete; fi
+
+distclean:
 	-rm -f html_data.c html_data.h $(VERSION_HEADER)
 	-rm -rf $(BUILDDIR)