File _link of Package mingw64-libpng

<link project="windows:mingw:win64" package="mingw64-libpng" baserev="648ae0924947a4b78979ee2313b35648">
  <patches>
    <delete name="libpng-1.6.19.tar.xz"/>
    <apply name="project.diff"/>
  </patches>
</link>