preparatory change to making SvXMLEnumMapEntry a template class for the
"UNO scoped enum" change.

But I think its an improvement by itself, there is no need to initialise
these arrays on-demand, the compiler will do that at link time.

Change-Id: Ie582fbe628cc9d21a4f31229c85195aa09139516
Reviewed-on: https://gerrit.libreoffice.org/34737Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>