test: fixed tst_qundogroup and removed CONFIG+=insignificant_test

This test had an invalid circular dependency: the test is in qtbase, and
it depends on lrelease in qttools, which depends on qtbase.

Change the test to skip if lrelease is not available or not working.

Change-Id: I964ddaf9485a2afed5a1bd4f88d9bdccadf1cfca
Reviewed-on: http://codereview.qt.nokia.com/2472
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Kalle Lehtonen <kalle.ju.lehtonen@nokia.com>

tests/auto/qundogroup/qundogroup.pro

@@ -1,5 +1,3 @@
 CONFIG += qttest_p4
 SOURCES += tst_qundogroup.cpp
 TARGET = tst_qundogroup
-
-CONFIG+=insignificant_test

tests/auto/qundogroup/tst_qundogroup.cpp

@@ -608,6 +608,11 @@ void tst_QUndoGroup::addStackAndDie()
 void tst_QUndoGroup::commandTextFormat()
 {
     QString binDir = QLibraryInfo::location(QLibraryInfo::BinariesPath);
+
+    if (QProcess::execute(binDir + "/lrelease -version") != 0) {
+        QSKIP("lrelease is missing or broken", SkipAll);
+    }
+
     QVERIFY(!QProcess::execute(binDir + "/lrelease testdata/qundogroup.ts"));
 
     QTranslator translator;