Ignore and clean generated assembly

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/Makefile b/library/Makefile
index c2e4a2c..304eeb6 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -400,10 +400,11 @@
 
 clean:
 ifndef WINDOWS
-	rm -f *.o libmbed*
-	rm -f $(OBJS_CRYPTO)
+	rm -f *.o *.s libmbed*
+	rm -f $(OBJS_CRYPTO) $(OBJS_CRYPTO:.o=.s)
 else
 	if exist *.o del /Q /F *.o
+	if exist *.s del /Q /F *.s
 	if exist libmbed* del /Q /F libmbed*
 	del /Q /F del_errors_out_if_the_file_list_is_empty_but_not_if_a_file_does_not_exist $(subst /,\,$(OBJS_CRYPTO))
 endif