rpcrt4: Fix potential memory leaks on error paths in RPCRT4_io_thread.

dlls/rpcrt4/rpc_server.c

@@ -391,6 +391,7 @@ static DWORD CALLBACK RPCRT4_io_thread(LPVOID the_arg)
 
     packet = HeapAlloc(GetProcessHeap(), 0, sizeof(RpcPacket));
     if (!packet) {
+      I_RpcFree(msg->Buffer);
       HeapFree(GetProcessHeap(), 0, msg);
       break;
     }
@@ -399,6 +400,7 @@ static DWORD CALLBACK RPCRT4_io_thread(LPVOID the_arg)
     packet->msg = msg;
     if (!QueueUserWorkItem(RPCRT4_worker_thread, packet, WT_EXECUTELONGFUNCTION)) {
       ERR("couldn't queue work item for worker thread, error was %d\n", GetLastError());
+      I_RpcFree(msg->Buffer);
       HeapFree(GetProcessHeap(), 0, msg);
       HeapFree(GetProcessHeap(), 0, packet);
       break;