l10ntools-transex3: make pParseQueue field private

Change-Id: Ieefed6e939e12b668a635eb8d7e70def2d52a85d
Reviewed-on: https://gerrit.libreoffice.org/11315
Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>
Tested-by: Norbert Thiebaud <nthiebaud@gmail.com>