[gtk-vnc] Default to bulding with GTK-3

[Daniel P. Berrange <dberrange src gnome org>]

commit c771332f8a269a1aeb4281a13b6f931e91d3fa7f
Author: Daniel P. Berrange <berrange redhat com>
Date:   Fri Jul 22 13:18:33 2016 +0100

    Default to bulding with GTK-3
    
    GTK-2 is pretty obsolete now, so we should default to
    using GTK-3
    
    Signed-off-by: Daniel P. Berrange <berrange redhat com>

 configure.ac |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 6145493..60fc378 100644
--- a/configure.ac
+++ b/configure.ac
@@ -91,12 +91,12 @@ dnl ****************************************************************************
 
 AC_MSG_CHECKING([which gtk+ version to compile against])
 AC_ARG_WITH([gtk],
-  [AS_HELP_STRING([--with-gtk=2.0|3.0],[which gtk+ version to compile against (default: 2.0)])],
+  [AS_HELP_STRING([--with-gtk=2.0|3.0],[which gtk+ version to compile against (default: 3.0)])],
   [case "$with_gtk" in
      2.0|3.0) ;;
      *) AC_MSG_ERROR([invalid gtk version specified]) ;;
    esac],
-  [with_gtk=2.0])
+  [with_gtk=3.0])
 AC_MSG_RESULT([$with_gtk])
 
 case "$with_gtk" in