Resolves fdo#84961: zh_CN date separator should be "/" rather than "／"

Thanks to the patch from Kevin Suo, see https://bugs.freedesktop.org/attachment.cgi?id=107768

Signed-off-by: Eike Rathke <erack@redhat.com>
With additional change to the DateAcceptancePattern.

Change-Id: I80695028d51c6b91e9e9418e2d1ce33d76d23893
Reviewed-on: https://gerrit.libreoffice.org/11958
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>