xmerge: If statement is redundant

Change-Id: I1d4000ae68d109ed01d4197a71f9175f79aa59f0
Reviewed-on: https://gerrit.libreoffice.org/10668
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>