Tests: Disable QTest crashhandler for plugin unit tests

Temporary workaround to avoid dead lock when executing
plugin unit test.

Change-Id: Ie6c3673d756ff3b67320bcc75d590933e58a5276
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/libs/extensionsystem/pluginmanager.cpp

@@ -1024,6 +1024,8 @@ static int executeTestPlan(const TestPlan &testPlan)
                 << QLatin1String("arg0") // fake application name
                 << QLatin1String("-maxwarnings") << QLatin1String("0"); // unlimit output
         qExecArguments << functions;
+        // avoid being stuck in QTBUG-24925
+        qExecArguments << "-nocrashhandler";
         failedTests += QTest::qExec(testObject, qExecArguments);
     }