wasm: fix single thread build

Fixes linking of apps

Pick-to: 6.6 6.7
Change-Id: I9bbec9b63af8ae2801643fe124aeda8b25abeca5
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

src/corelib/thread/qthread.cpp

@@ -1014,6 +1014,10 @@ bool QThread::isInterruptionRequested() const
     return false;
 }
 
+void QThread::setTerminationEnabled(bool)
+{
+}
+
 // No threads: so we can just use static variables
 Q_CONSTINIT static QThreadData *data = nullptr;