AutoTest: Fix possible crash

Re-triggering runOrDebugTests() should be done
only once to avoid the test runner interfering
itself and crashing QC.
Amends 0f60f120d2.

Change-Id: I49f666f2c96730729ef54d8d8781d4058b3e0cca
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/autotest/testrunner.cpp

@@ -456,8 +456,10 @@ void TestRunner::onBuildSystemUpdated()
     Target *target = SessionManager::startupTarget();
     if (QTC_GUARD(target))
         disconnect(target, &Target::buildSystemUpdated, this, &TestRunner::onBuildSystemUpdated);
-    m_skipTargetsCheck = true;
-    runOrDebugTests();
+    if (!m_skipTargetsCheck) {
+        m_skipTargetsCheck = true;
+        runOrDebugTests();
+    }
 }
 
 void TestRunner::runTests()