xmerge: Converting ArrayList to Array

Change-Id: I67c70ce05d35c8f40bea153499820e7e52c2ff08
Reviewed-on: https://gerrit.libreoffice.org/11748
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>