wifi: Silence some valgrind warnings

src/wifi/model/wifi-ppdu.cc

@@ -48,7 +48,8 @@ WifiPpdu::WifiPpdu (const WifiConstPsduMap & psdus, WifiTxVector txVector, Time
     m_psdus (psdus),
     m_truncatedTx (false),
     m_band (band),
-    m_channelWidth (txVector.GetChannelWidth ())
+    m_channelWidth (txVector.GetChannelWidth ()),
+    m_txPowerLevel (txVector.GetTxPowerLevel ())
 {
   NS_LOG_FUNCTION (this << psdus << txVector << ppduDuration << band);
   if (m_preamble == WIFI_PREAMBLE_HE_MU)

src/wifi/test/tx-duration-test.cc

@@ -20,6 +20,7 @@
  */
 
 #include "ns3/log.h"
+#include "ns3/simulator.h"
 #include "ns3/test.h"
 #include "ns3/yans-wifi-phy.h"
 #include "ns3/he-ru.h"
@@ -566,6 +567,8 @@ TxDurationTest::DoRun (void)
                           40, 800, NanoSeconds (1489600));
 
   NS_TEST_EXPECT_MSG_EQ (retval, true, "an 802.11ax MU duration failed");
+
+  Simulator::Destroy ();
 }
 
 /**