File _link of Package virtualbox

<link project="openSUSE:Factory" package="virtualbox">
<patches>
  <!-- <branch /> for a full copy, default case  -->
  <!-- <apply name="patch" /> apply a patch on the source directory  -->
  <!-- <topadd>%define build_with_feature_x 1</topadd> add a line on the top (spec file only) -->
  <!-- <add name="file.patch" /> add a patch to be applied after %setup (spec file only) -->
  <!-- <delete name="filename" /> delete a file -->
</patches>
</link>