The Mapping struct is small, so there's no need to reuse it.
Without this, sc/qa/.../sumif_wildcards.fods sometimes fails with calc
threading.

Change-Id: If1f370bebe8e1afa14f8645d843a056b6f0dbdea
Reviewed-on: https://gerrit.libreoffice.org/56449
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>