and update the sum-range token in RPN array while creation of
the RPN array itself.

+ Adds unit tests.
+ In ScParallelismTest unit test, enable threading in its setUp()
  method and restore the original setting in tearDown().

Change-Id: Iee9b7759210a82950181a418eb92766a6cf891fc
Reviewed-on: https://gerrit.libreoffice.org/49465Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Eike Rathke <erack@redhat.com>