Do not trigger an error when Qt is missing, too old or not working.

	* configure.ac: Here.
	Protect a test from a variable expanding to an empty string.

ChangeLog

+2010-10-22  Roland Levillain  <roland@lrde.epita.fr>
+
+	Do not trigger an error when Qt is missing, too old or not working.
+
+	* configure.ac: Here.
+	Protect a test from a variable expanding to an empty string.
+
 2010-10-22  Roland Levillain  <roland@lrde.epita.fr>
 
 	Have AutoTroll always restore the initial ``current directory''.

configure.ac

@@ -216,8 +216,8 @@ AM_CONDITIONAL(HAVE_MAGICKXX, test "x$oln_have_magickxx" = xyes)
 # Qt.  #
 # ---- #
 
-AT_WITH_QT([xml], [], [], [], [oln_have_qt=yes])
-if test $oln_have_qt = yes; then
+AT_WITH_QT([xml], [], [], [:], [oln_have_qt=yes])
+if test x$oln_have_qt = xyes; then
   AT_REQUIRE_QT_VERSION([4],
     AC_MSG_WARN([Qt-dependent programs will be disabled.]),
     oln_have_expected_qt_version=yes)