long to sal_Int32

Change-Id: I03c3d93c03239ae39bb3078ffabe71276ec37d25
Reviewed-on: https://gerrit.libreoffice.org/7658
Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>
Tested-by: Norbert Thiebaud <nthiebaud@gmail.com>