don't stop if qt is not found; more elegant way for adding qt rules

m4/ax_check_qt.m4

@@ -79,9 +79,16 @@ AC_DEFUN([AX_CXX_CHECK_QT], [
       AM_CPPFLAGS+=" ${$1_CFLAGS}"
       AM_CXXFLAGS+=" ${$1_CFLAGS}"
       LIBS+=" ${$1_LIBS}"
-    ])
+    ], [HAVE_$1=0])
   ])
   AM_CONDITIONAL(HAVE_$1, test $HAVE_$1 -eq 1)
   AC_SUBST(AM_CPPFLAGS)
   AC_SUBST(AM_CXXFLAGS)
+  AM_QT_RULES='
+%_ui.hxx: %.ui
+	${UIC} -o [$][@] $<
+
+moc_%.cxx: %.hxx
+	${MOC} -o [$][@] $<'
+  AC_SUBST(QT_RULES)
 ])