Bump debhelper compatibility to 9

Update versioned debhelper build-dependency

debian/changelog

@@ -68,6 +68,8 @@ xen-tools (4.4~dev-1) UNRELEASED; urgency=low
       dh_auto_* can't help. No more explicitly call "make manpages", it's
       a depedency of "make install" in the next line anyway.
     - Finally switch to a minimal dh style debian/rules.
+  * Bump debhelper compatibility to 9
+    - Update versioned debhelper build-dependency
   * Bump copyright years in debian/copyright.
   * Apply wrap-and-sort.
 

debian/compat

@@ -1 +1 @@
-7
+9

debian/control

@@ -2,7 +2,7 @@ Source: xen-tools
 Section: utils
 Priority: extra
 Maintainer: Axel Beckert <abe@debian.org>
-Build-Depends: debhelper (>= 7.0.0),
+Build-Depends: debhelper (>= 9~),
                devscripts,
                git,
                libfile-slurp-perl,