bug#20055: libvpx: Dangling .so references

[Taylan Ulrich Bayırlı/Kammer]

(See the first "Dangling .so references" bug report for more
information.)

/gnu/store/rifn72fhlvsgkvlwyy0cfy61kqpbfv4i-libvpx-1.3.0/

  
/gnu/store/rifn72fhlvsgkvlwyy0cfy61kqpbfv4i-libvpx-1.3.0/bin/vp8_scalable_patterns
        libvpx.so.1 => not found
  /gnu/store/rifn72fhlvsgkvlwyy0cfy61kqpbfv4i-libvpx-1.3.0/bin/vpxdec
        libvpx.so.1 => not found
  
/gnu/store/rifn72fhlvsgkvlwyy0cfy61kqpbfv4i-libvpx-1.3.0/bin/vp9_spatial_scalable_encoder
        libvpx.so.1 => not found
  /gnu/store/rifn72fhlvsgkvlwyy0cfy61kqpbfv4i-libvpx-1.3.0/bin/vpxenc
        libvpx.so.1 => not found