Fix leak of 'msg' object in client stream code

In one exit path we forgot to free the virNetMessage object causing
a large memory leak for streams which send a lot of data. Some other
paths were calling VIR_FREE directly instead of virNetMessageFree
although this was (currently) harmless.

* src/rpc/virnetclientstream.c: Fix leak of msg object
* src/rpc/virnetclientprogram.c: Call virNetMessageFree instead
  of VIR_FREE

src/rpc/virnetclientprogram.c

@@ -329,11 +329,11 @@ int virNetClientProgramCall(virNetClientProgramPtr prog,
         goto error;
     }
 
-    VIR_FREE(msg);
+    virNetMessageFree(msg);
 
     return 0;
 
 error:
-    VIR_FREE(msg);
+    virNetMessageFree(msg);
     return -1;
 }

src/rpc/virnetclientstream.c

@@ -361,11 +361,12 @@ int virNetClientStreamSendPacket(virNetClientStreamPtr st,
     if (virNetClientSend(client, msg, wantReply) < 0)
         goto error;
 
+    virNetMessageFree(msg);
 
     return nbytes;
 
 error:
-    VIR_FREE(msg);
+    virNetMessageFree(msg);
     return -1;
 }