xmerge: Remove local variable name conflict

Change-Id: Iab2fdc516f5074a6957bde3be7aec52e48cbdc4b
Reviewed-on: https://gerrit.libreoffice.org/10663
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>