Disable D-Bus if installed version is < 1.0.0 and warns the user.

Adds an option to force D-Bus support to be enabled anyway.

configure.ac

@@ -864,6 +864,25 @@ then
           VLC_ADD_LDFLAGS([dbus],[$DBUS_LIBS])
           VLC_ADD_CFLAGS([dbus],[$DBUS_CFLAGS])
         fi],
+
+    if ${PKG_CONFIG} --exists dbus-1
+    then
+      [AC_ARG_ENABLE(old-dbus,
+        [  --enable-old-dbus      Deprecated D-Bus support (default disabled)])]
+
+      if test "${enable_old_dbus}" != "yes"
+      then
+        echo ""
+        echo "****** WARNING **** WARNING ***** WARNING *************"
+        echo "*** Your D-Bus version is < 1.0.0"
+        echo "*** You are using old and buggy software and so"
+        echo "*** D-Bus support has been disabled."
+        echo "*** Please upgrade D-Bus : http://dbus.freedesktop.org"
+        echo "*** Alternatively you can force the use of your old and"
+        echo "*** buggy D-Bus version by specifying --enable-old-dbus"
+        echo "*******************************************************"
+        echo ""
+      else
         dnl not too old dbus
         [ PKG_CHECK_MODULES(DBUS, dbus-1 >= 0.92,
           [ AC_DEFINE( HAVE_DBUS_2, 1, [Define if you have the D-BUS library API >= 0.92] )
@@ -886,6 +905,8 @@ then
             ]
           )]
         )]
+      fi
+    fi
   )
 fi