emulators/rpcs3: fails to build on FreeBSD < 13 after 31b321b68b42

ld: error: undefined symbol: std::1::cxx_atomic_notify_one(std::1::cxx_atomic_impl<long, std::1::cxx_atomic_base_impl<long> > const volatile*)

referenced by rpcn_client.cpp

rpcn_client.cpp.o:(rpcn::rpcn_client::rpcn_client()) in archive rpcs3/Emu/librpcs3_emu.a

referenced by rpcn_client.cpp

rpcn_client.cpp.o:(rpcn::rpcn_client::rpcn_thread()) in archive rpcs3/Emu/librpcs3_emu.a

referenced by rpcn_client.cpp

rpcn_client.cpp.o:(rpcn::rpcn_client::~rpcn_client()) in archive rpcs3/Emu/librpcs3_emu.a

referenced 9 more times

ld: error: undefined symbol: std::1::libcpp_atomic_wait(std::1::cxx_atomic_impl<long, std::1::cxx_atomic_base_impl<long> > const volatile*, long)

referenced by rpcn_client.cpp

rpcn_client.cpp.o:(bool std::__1::__libcpp_thread_poll_with_backoff<std::__1::__atomic_semaphore_base::acquire()::'lambda'() const&, std::__1::__libcpp_atomic_wait_backoff_impl<std::__1::__cxx_atomic_impl<long, std::__1::__cxx_atomic_base_impl<long> >, std::__1::__atomic_semaphore_base::acquire()::'lambda'()>&>(std::__1::__atomic_semaphore_base::acquire()::'lambda'() const&, std::__1::__libcpp_atomic_wait_backoff_impl<std::__1::__cxx_atomic_impl<long, std::__1::__cxx_atomic_base_impl<long> >, std::__1::__atomic_semaphore_base::acquire()::'lambda'()>&, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> >)) in archive rpcs3/Emu/librpcs3_emu.a

ld: error: undefined symbol: std::1::libcpp_atomic_monitor(std::1::cxx_atomic_impl<long, std::1::cxx_atomic_base_impl<long> > const volatile*)

referenced by rpcn_client.cpp

rpcn_client.cpp.o:(bool std::__1::__libcpp_thread_poll_with_backoff<std::__1::__atomic_semaphore_base::acquire()::'lambda'() const&, std::__1::__libcpp_atomic_wait_backoff_impl<std::__1::__cxx_atomic_impl<long, std::__1::__cxx_atomic_base_impl<long> >, std::__1::__atomic_semaphore_base::acquire()::'lambda'()>&>(std::__1::__atomic_semaphore_base::acquire()::'lambda'() const&, std::__1::__libcpp_atomic_wait_backoff_impl<std::__1::__cxx_atomic_impl<long, std::__1::__cxx_atomic_base_impl<long> >, std::__1::__atomic_semaphore_base::acquire()::'lambda'()>&, std::__1::chrono::duration<long long, std::__1::ratio<1l, 1000000000l> >)) in archive rpcs3/Emu/librpcs3_emu.a

clang++: error: linker command failed with exit code 1 (use -v to see invocation)

(cherry picked from commit 6551900e74bb291302cd2866376fdc326d5f2b22)