tools/libxl: add missing items to clean target

Some generated files are not removed by "make clean". Add them.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wl@xen.org>

tools/libxl/Makefile

@@ -370,8 +370,10 @@ clean:
 	$(RM) -f _*.h *.o *.so* *.a $(CLIENTS) $(DEPS_RM)
 	$(RM) -f _*.c *.pyc _paths.*.tmp _*.api-for-check
 	$(RM) -f testidl.c.new testidl.c *.api-ok
+	$(RM) -f $(TEST_PROGS)
 	$(RM) -f xenlight.pc
 	$(RM) -f xlutil.pc
+	$(RM) -rf __pycache__
 	$(MAKE) -C $(ACPI_PATH) ACPI_BUILD_DIR=$(CURDIR) clean
 
 distclean: clean