Make the experimental Networking TS code work without std::mutex and
std::condition_variable.
libstdc++-v3/ChangeLog:
PR libstdc++/89760
* include/experimental/executor [!_GLIBCXX_HAS_GTHREADS]:
(execution_context::mutex_type): Define dummy mutex type.
(system_context): Use execution_context::mutex_type.
(system_context) [!_GLIBCXX_HAS_GTHREADS]: Define dummy
thread and condition variable types.
[!_GLIBCXX_HAS_GTHREADS] (system_context::_M_run()): Do not
define.
(system_context::_M_post) [!_GLIBCXX_HAS_GTHREADS]: Throw
an exception when threads aren't available.
(strand::running_in_this_thread()): Defer to _M_state.
(strand::_State::running_in_this_thread()): New function.
(use_future_t): Do not depend on _GLIBCXX_USE_C99_STDINT_TR1.
* include/experimental/io_context (io_context): Use the
execution_context::mutex_type alias. Replace stack of thread
IDs with counter.
* testsuite/experimental/net/execution_context/use_service.cc:
Enable test for non-pthread targets.
18095be170