Mark external/mdds/gcc9.patch as upstreamed

Change-Id: I146dd8926e5e93a57162558286168e963f402f59
Reviewed-on: https://gerrit.libreoffice.org/58689
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

external/mdds/UnpackedTarball_mdds.mk

@@ -14,7 +14,9 @@ $(eval $(call gb_UnpackedTarball_set_tarball,mdds,$(MDDS_TARBALL)))
 $(eval $(call gb_UnpackedTarball_set_patchlevel,mdds,0))
 
 # c++17.patch upstreamed as <https://gitlab.com/mdds/mdds/merge_requests/11> "Remove some
-# unnecessary uses of obsolete std::unary_function":
+#  unnecessary uses of obsolete std::unary_function";
+# gcc9.patch upstreamed at <https://gitlab.com/mdds/mdds/merge_requests/14> "Remove unnecessary
+#  user-provided special members that cause -Wdeprecated-copy":
 $(eval $(call gb_UnpackedTarball_add_patches,mdds,\
     external/mdds/c++17.patch \
     external/mdds/gcc9.patch \