Fix issues in the libc-wasi poll_oneoff when thread-mgr is enabled (#1980)

Fix issues in the libc-wasi `poll_oneoff` when thread manager is enabled:
-  The exception of a thread may be cleared when other thread runs into
   `proc_exit` and then calls `clear_wasi_proc_exit_exception`, so should not
   use `wasm_runtime_get_exception` to check whether an exception was
    thrown, use `wasm_cluster_is_thread_terminated` instead
- We divided one time poll_oneoff into many times poll_oneoff to check
   the exception to avoid long time waiting in previous PR, but if all events
   returned by one time poll are all waiting events, we need to continue to
   wait but not return directly.

Follow-up on #1951. Tested with multiple timeout values, with and without
interruption and measured the time spent sleeping.

core/iwasm/libraries/thread-mgr/thread_manager.c

@@ -1198,3 +1198,9 @@ wasm_cluster_spread_custom_data(WASMModuleInstanceCommon *module_inst,
         os_mutex_unlock(&cluster->lock);
     }
 }
+
+bool
+wasm_cluster_is_thread_terminated(WASMExecEnv *exec_env)
+{
+    return (exec_env->suspend_flags.flags & 0x01) ? true : false;
+}