maint: Bump version number to 4.0.0

As documented in

  https://libvirt.org/downloads.html#schedule
  https://libvirt.org/downloads.html#numbering

the next release will happen in the middle of January 2018 and,
being the first release of a new year, will bring a brand new
major version number with it.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>

configure.ac

@@ -16,7 +16,7 @@ dnl You should have received a copy of the GNU Lesser General Public
 dnl License along with this library.  If not, see
 dnl <http://www.gnu.org/licenses/>.
 
-AC_INIT([libvirt], [3.11.0], [libvir-list@redhat.com], [], [https://libvirt.org])
+AC_INIT([libvirt], [4.0.0], [libvir-list@redhat.com], [], [https://libvirt.org])
 AC_CONFIG_SRCDIR([src/libvirt.c])
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_HEADERS([config.h])

docs/news.xml

@@ -33,7 +33,7 @@
      -->
 
 <libvirt>
-  <release version="v3.11.0" date="unreleased">
+  <release version="v4.0.0" date="unreleased">
     <section title="New features">
     </section>
     <section title="Improvements">