Put DebugSymbolResolver and FatalSignalHandler in an unnamed namespace

Pick-to: 6.3
Change-Id: I5ff8e16fcdcb4ffd9ab6fffd16eb735315b337b6
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/testlib/qtestcase.cpp

@@ -1670,6 +1670,9 @@ void TestMethods::invokeTests(QObject *testObject) const
     QSignalDumper::endDump();
 }
 
+} // namespace QTest
+
+namespace {
 #if defined(Q_OS_WIN)
 
 // Helper class for resolving symbol names by dynamically loading "dbghelp.dll".
@@ -1970,7 +1973,7 @@ private:
 bool FatalSignalHandler::pauseOnCrash = false;
 #endif // defined(Q_OS_UNIX) && !defined(Q_OS_WASM)
 
-} // namespace
+} // unnamed namespace
 
 static void initEnvironment()
 {