Update test configurations (remove /await and skips, add missing options)

[StephanTLavavej]

• Remove /await from test configurations.
  • Mentioned in P0912R5 Library Support For Coroutines #40.
  • Remove #ifdef _RESUMABLE_FUNCTIONS_SUPPORTED blocks in VSO_0000000_instantiate_iterators_misc.
• Update VSO_0157762_feature_test_macros/env.lst comment.
  • Now this mentions another intentional difference from usual_matrix.lst.
• Add missing /fp:strict to MEOW_winsdk_matrix.lst.
• Add missing /Zc:noexceptTypes- to locale0_implib_cpp_matrix.lst.
• Remove VSO-1093670 workaround.
• Unskip a configuration of VSO_0000000_string_view_idl.
  • This was skipped by Run format validation as its own stage and enable /BE #682 on 2020-04-09. At the time, we were using VS 2019 16.6 Preview 2 (Update to Clang 10 and Visual Studio 2019 version 16.6p2 #645 merged on 2020-03-28). Now we're using VS 2019 16.8 Preview 1, and I can't reproduce this ICE locally. I ran x86 and x64, 30 times each, and they all passed. Let's try restoring this configuration.

The rationale for removing /await coverage is that the STL is almost completely insensitive to this option. The only places we detect it are Standard <coroutine> where it's simply rejected:

STL/stl/inc/coroutine

Lines 12 to 15 in 3cca473

	#ifdef _RESUMABLE_FUNCTIONS_SUPPORTED
	#pragma message("The contents of <coroutine> are not available with /await.")
	#pragma message("Remove /await for standard coroutines or use <experimental/coroutine> for legacy /await support.")
	#else // ^^^ /await ^^^ / vvv no /await vvv

and <future> which defines support machinery:

STL/stl/inc/future

Lines 1505 to 1599 in 3cca473

	#ifdef _RESUMABLE_FUNCTIONS_SUPPORTED
	// Experimental coroutine support for std::future. Subject to change/removal!
	namespace experimental {
	template <class _Ty, class... _ArgTypes>
	struct coroutine_traits<future<_Ty>, _ArgTypes...> {
	// defines resumable traits for functions returning future<_Ty>
	struct promise_type {
	promise<_Ty> _MyPromise;
	future<_Ty> get_return_object() {
	return _MyPromise.get_future();
	}
	suspend_never initial_suspend() const noexcept {
	return {};
	}
	suspend_never final_suspend() const noexcept {
	return {};
	}
	template <class _Ut>
	void return_value(_Ut&& _Value) {
	_MyPromise.set_value(_STD forward<_Ut>(_Value));
	}
	void unhandled_exception() {
	_MyPromise.set_exception(_STD current_exception());
	}
	};
	};
	template <class... _ArgTypes>
	struct coroutine_traits<future<void>, _ArgTypes...> {
	// defines resumable traits for functions returning future<void>
	struct promise_type {
	promise<void> _MyPromise;
	future<void> get_return_object() {
	return _MyPromise.get_future();
	}
	suspend_never initial_suspend() const noexcept {
	return {};
	}
	suspend_never final_suspend() const noexcept {
	return {};
	}
	void return_void() {
	_MyPromise.set_value();
	}
	void unhandled_exception() {
	_MyPromise.set_exception(_STD current_exception());
	}
	};
	};
	template <class _Ty>
	struct _Future_awaiter {
	future<_Ty>& _Fut;
	bool await_ready() const {
	return _Fut._Is_ready();
	}
	void await_suspend(experimental::coroutine_handle<> _ResumeCb) {
	// TRANSITION, change to .then if and when future gets .then
	thread _WaitingThread([&_Fut = _Fut, _ResumeCb]() mutable {
	_Fut.wait();
	_ResumeCb();
	});
	_WaitingThread.detach();
	}
	decltype(auto) await_resume() {
	return _Fut.get();
	}
	};
	} // namespace experimental
	// Coroutines TS and C++20 coroutine adapter.
	template <class _Ty>
	auto operator co_await(future<_Ty>&& _Fut) {
	return experimental::_Future_awaiter<_Ty>{_Fut};
	}
	template <class _Ty>
	auto operator co_await(future<_Ty>& _Fut) {
	return experimental::_Future_awaiter<_Ty>{_Fut};
	}
	#endif // _RESUMABLE_FUNCTIONS_SUPPORTED

/await coverage for that support machinery remains in a single test:

STL/tests/std/tests/VSO_0971246_legacy_await_headers/env.lst

Lines 4 to 11 in 3cca473

	RUNALL_INCLUDE ..\prefix.lst
	RUNALL_CROSSLIST
	PM_CL="/EHsc /MT /std:c++latest /permissive-"
	PM_CL="/EHsc /MT /std:c++latest /permissive"
	PM_CL="/EHsc /MT /std:c++latest /permissive- /await"
	PM_CL="/EHsc /MT /std:c++latest /permissive /await"
	PM_CL="/BE /c /EHsc /MD /std:c++latest /permissive- /await"
	PM_CL="/BE /c /EHsc /MD /std:c++latest /permissive-"

Now that Standard coroutines have been finalized, we know that the experimental support machinery won't be needed for C++20 support, so there's no reason to test it everywhere.