mlite notifications: fixed configure issues

Explicit --enable-mlite didn't enable mlite (enable_mlite not set).
The default is now to not enable it in any case (even if available),
so traditional users won't have to add --disable-mlite to suppress
the error about it being not installed.

The code which depends on mlite must not be compiled if the feature
is disabled, because if mlite is not installed, it would cause compile
errors.

configure-pre.in

@@ -506,11 +506,16 @@ if test $enable_dbus_service = "yes"; then
     PKG_CHECK_MODULES(MLITE, [mlite QtGui], HAVE_MLITE=yes, HAVE_MLITE=no)
     AC_ARG_ENABLE(mlite,
                   AS_HELP_STRING([--enable-mlite],
-                                 [send notifications for automatic sync events, using mlite]),
-                  [ test "$enableval" = "no" || test $HAVE_MLITE = "yes" || AC_ERROR([required mlite package not found]) ],
-                  [ test $HAVE_MLITE = "yes" || AC_ERROR([required mlite package not found, use --disable-mlite to compile without mlite based notifications]) ])
-    if test $HAVE_MLITE = "yes"; then
+                                 [send notifications for automatic sync events, using mlite (off by default)]),
+                  [ enable_mlite="$enableval"
+                    test "$enableval" = "no" || test $HAVE_MLITE = "yes" || AC_ERROR([required mlite package not found]) ],
+                  [ enable_mlite="no" ])
+    if test $enable_mlite = "yes"; then
         AC_DEFINE(HAS_MLITE, 1, [define if mlite could be used in dbus service])
+    else
+        # don't use mlite, even if found
+        MLITE_CFLAGS=
+        MLITE_LIBS=
     fi
     AC_DEFINE(DBUS_SERVICE, 1, [define if dbus service is enabled])
 fi
@@ -522,8 +527,6 @@ AC_SUBST(KEYRING_CFLAGS)
 AC_SUBST(KEYRING_LIBS) 
 AC_SUBST(LIBNOTIFY_CFLAGS)
 AC_SUBST(LIBNOTIFY_LIBS)
-AC_SUBST(MLITE_CFLAGS)
-AC_SUBST(MLITE_LIBS)
 AC_SUBST(LIBEXECDIR)
 AC_SUBST(BUTEOSYNCPROFILE_LIBS)
 AC_SUBST(BUTEOSYNCPROFILE_CFLAGS)

src/NotificationBackendMLite.cpp

@@ -17,6 +17,10 @@
  * 02110-1301  USA
  */
 
+#include <config.h>
+
+#ifdef HAS_MLITE
+
 #include "NotificationBackendMLite.h"
 
 #include <mlite/MNotification>
@@ -63,3 +67,4 @@ void NotificationBackendMLite::publish(
 
 SE_END_CXX
 
+#endif