Bug 1499864 - WindowsNetworkFunctionsWrapper's dtor should be virtual. r=bagder

Also delete declaration of an unused var.
Both of these are compile warnings on win64 clang-cl.

MozReview-Commit-ID: aOBmtxgpz6

Differential Revision: https://phabricator.services.mozilla.com/D9029

--HG--
extra : moz-landing-system : lando

toolkit/system/windowsDHCPClient/DHCPUtils.cpp

@@ -41,7 +41,6 @@ GetActiveDHCPNetworkAdapterName(nsACString& aNetworkAdapterName,
 {
   /* Declare and initialize variables */
 
-  uint32_t dwSize = 0;
   uint32_t dwRetVal = 0;
   nsresult rv = NS_ERROR_FAILURE;
 

toolkit/system/windowsDHCPClient/WindowsNetworkFunctionsWrapper.h

@@ -49,7 +49,7 @@ class WindowsNetworkFunctionsWrapper : nsISupports
   );
 
   protected:
-    ~WindowsNetworkFunctionsWrapper(){};
+    virtual ~WindowsNetworkFunctionsWrapper(){};
 
 };