debian/control: xz-utils is not pseudo-essential any more

Since dpkg 1.16.4~6 (libdpkg: Add liblzma compression support,
2012-06-07), the xz command is no longer needed in a minimal Debian
system.

Based on its list of reverse-dependencies, it is even safe to lower
the priority to optional.  Let's make it "standard", since it is not
part of the traditional Unix toolset but is a useful component even in
reasonably small character-mode systems.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
diff --git a/debian/changelog b/debian/changelog
index 9317f3a..ca2427f 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -9,8 +9,9 @@
       at run time.
       Closes: #919950.  Thanks to Josh Triplett.
     - Breaks: liblzma2 versions without symbol versioning.
-  * xz-utils/README.Debian: Remove notes about differences from
-    upstream.
+  * xz-utils:
+    - Lower priority of xz-utils to standard.  Closes: #685203.
+    - README.Debian: Remove notes about differences from upstream.
 
  -- Jonathan Nieder <jrnieder@gmail.com>  Sun, 27 Jan 2019 15:02:13 -0800
 
diff --git a/debian/control b/debian/control
index 59ccae3..ea7ad64 100644
--- a/debian/control
+++ b/debian/control
@@ -30,6 +30,7 @@
  format, use the p7zip package instead.)
 
 Package: xz-utils
+Priority: standard
 Architecture: any
 Depends: ${shlibs:Depends}, ${misc:Depends}
 Multi-Arch: foreign