Initialize the ssl variable in QHttpNetworkRequestPrivate

Address the "A constructor must initialize all data members of the
class" warning.

Found by an Axivion Scan.

Task-number: QTBUG-125026
Pick-to: 6.8 6.7 6.5
Change-Id: If78cde6a9c3771eb87e62729523b848f2efc2d83
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

src/network/access/qhttpnetworkrequest_p.h

@@ -152,7 +152,7 @@ public:
     bool http2Direct;
     bool h2cAllowed = false;
     bool withCredentials;
-    bool ssl;
+    bool ssl = false;
     bool preConnect;
     bool needResendWithCredentials = false;
     int redirectCount;