QNativeSocketEngine: declare PacketHeaderOption enum as a bit field

It should be possible to use these constants simultaneously and to
handle them separately from each other.

Change-Id: I0c48a3c25456b487c9d6139b05105ada20f34be6
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/network/socket/qabstractsocketengine_p.h

@@ -125,9 +125,9 @@ public:
 
     enum PacketHeaderOption {
         WantNone = 0,
-        WantDatagramSender,
-        WantDatagramDestination,
-        WantDatagramHopLimit,
+        WantDatagramSender = 0x01,
+        WantDatagramDestination = 0x02,
+        WantDatagramHopLimit = 0x04,
 
         WantAll = 0xff
     };