add namespace for currentThreadEventLoop and when there is no worker thread loop, acceptor_loop should also be returned

[fuzhufang]

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[fuzhufang]

In the static method onAccept, When the worker thread loop is not obtained, acceptor_loop is also used. Therefore, in method: EventLoopPtr loop (int idx=-1), when there is no worker thread loop, acceptor_loop should also be returned Otherwise, in a scenario where there is only one acceptor_loop no worker loop, calling the loop method will return null, resulting in a segment error when using it

#Define currentThreadEventLoop tlsEventLoop() to define the namespace ::hv:: , otherwise using currentThreadEventLoop in a non hv namespace will result in an error