New upstream git snapshot

* New upstream git snapshot with support for peer-to-peer software
  collections, required by Flatpak's peer-to-peer app sharing feature
  - d/copyright: Update
  - d/libostree-1-1.symbols: Update
  - Build-depend on Avahi libraries

debian/control

@@ -25,6 +25,8 @@ Build-Depends:
  gtk-doc-tools <!nodoc>,
  libarchive-dev,
  libattr1-dev,
+ libavahi-client-dev (>= 0.6.31),
+ libavahi-glib-dev (>= 0.6.31),
  libcap-dev,
  libfuse-dev,
  libgirepository1.0-dev,