Signals not received when building with link time optimization enabled and using asio as static library

We are using asio as a static library instead of header only, boost version 1.78. We instantiate a `boost::asio::signal_set` in the main thread of our application but do not receive any signals when building with link time optimization enabled (using gcc9/10). With making `get_signal_state()` (signal_set_service.ipp) `BOOST_NOINLINE` the issue does not occur and signals are again received properly.

Start with signal_set_service.ipp and inspect get_signal_state() in the static-library build path. Reproduce the issue with Boost 1.78, GCC 9 or 10, link-time optimization, and asio signal_set in the main thread. Done means signals are received reliably without requiring the reported workaround.

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