Record external/harfbuzz/msvc.patch as sent upstream

Change-Id: I47277272170508e9af7617e9b774bbdca05e9ec3
Reviewed-on: https://gerrit.libreoffice.org/68766
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

external/harfbuzz/UnpackedTarball_harfbuzz.mk

@@ -15,6 +15,8 @@ $(eval $(call gb_UnpackedTarball_update_autoconf_configs,harfbuzz))
 
 $(eval $(call gb_UnpackedTarball_set_patchlevel,harfbuzz,0))
 
+# * external/harfbuzz/msvc.patch sent upstream as <https://github.com/harfbuzz/harfbuzz/pull/1605>
+#   "Fix hb_atomic_* variants based on C++11 atomics":
 $(eval $(call gb_UnpackedTarball_add_patches,harfbuzz, \
     external/harfbuzz/msvc.patch \
 ))