xmerge: replace package.html with package-info.java

Change-Id: Ia11a2da8ffd9be6942e52b84937d3aa15a1ecb82
Reviewed-on: https://gerrit.libreoffice.org/11221
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>