This reverts commit 8bc951da.

As discussed at
<https://lists.freedesktop.org/archives/libreoffice/2018-April/079955.html>
"long->sal_Int32 in tools/gen.hxx", that commit caused lots of problems with
signed integer overflow, and the original plan was to redo it to consistently
use sal_Int64 instead of sal_Int32.  <https://gerrit.libreoffice.org/#/c/52471/>
"sal_Int32->sal_Int64 in tools/gen.hxx" tried that.  However, it failed
miserably on Windows, causing odd failures like not writing out Pictures/*.svm
streams out into .odp during CppunitTest_sd_export_ooxml2.  So the next best
approach is to just revert the original commit, at least for now.

Includes revert of follow-up 8c50aff2 "Fix
Library_vclplug_qt5".

Change-Id: Ia8bf34272d1ed38aac00e5d07a9d13fb03f439ae
Reviewed-on: https://gerrit.libreoffice.org/52532Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>