[0.4.8] cherry-pick [IPHLPAPI] Fix memory leak in getNumRoutes. CORE-14353

Thx for that gem Thomas. I let it idle for an hour. It solves the leak.
cherry-picked by Joachim Henze

Author: ThFabba

dll/win32/iphlpapi/ipstats_reactos.c

@@ -397,6 +397,7 @@ DWORD getNumRoutes(void)
 
     TRACE("numRoutes: %d\n", (int)numRoutes);
 
+    tdiFreeThingSet( entitySet );
     closeTcpFile( tcpFile );
 
     return numRoutes;