Mark Debian 8 Jessie as EoL

Reasoning:

Debian 8 Jessie has still (external) ELTS until 2022. But
debian-internal LTS has ended and it will likely vanish from the
normal mirrors soon. And it is already available in the archive. (And
some architectures are already only available in the archive.)

Also mention marking Debian 7 Wheezy as EoL in NEWS.markdown. (Was
already mentioned in debian/changelog.)

NEWS.markdown

@@ -18,6 +18,8 @@ Distribution Releases Changes
     despite mentioned in this file.)
   + Ubuntu 18.10 Cosmic Cuttlefish
   + Ubuntu 19.04 Disco Dingo
+  + Debian 7 Wheezy
+  + Debian 8 Jessie
 
 
 xen-tools 4.8 (released 9 Feb 2019)

debian/changelog

@@ -1,7 +1,7 @@
 xen-tools (4.8.1~dev-1) UNRELEASED; urgency=medium
 
   * New upstream bugfix release.
-    + Mark Debian 7 Wheezy as EoL.
+    + Mark Debian 7 Wheezy and 8 Jessie as EoL.
     + Update list of Ubuntu releases.
     + distributions.conf: Fix typo in release name of future Debian 12
       release (bookwork → bookworm).

etc/distributions.conf

@@ -13,7 +13,7 @@ etch         = debian eol
 lenny        = debian eol
 squeeze      = debian eol default-keyring
 wheezy       = debian eol
-jessie       = debian
+jessie       = debian eol
 stretch      = debian
 buster       = debian
 bullseye     = debian dont-test