is_mutex_type<recursive_mutex> is false if BOOST_NO_CXX11_SFINAE_EXPR is defined

[jwakely]

This part of the old has_member_try_lock implementation fails to match recursive_mutex::try_lock() because it's noexcept:

thread/include/boost/thread/lockable_traits.hpp

Lines 143 to 146 in 4abafcc

	template<typename U>
	static true_type has_member(bool (U::*)());
	template<typename U>
	static false_type has_member(U);

The bug is still there in the current code, but hidden by a35ffa3 which has a working version that is used by most compilers since Boost 1.69.0

A fix would be to add another partial specialization for noexcept functions:

#ifndef BOOST_NO_CXX11_NOEXCEPT
        template<typename U>
        static true_type has_member(bool (U::*)() noexcept);
#endif

[jwakely]

Demo of the bug in 1.66.0: https://godbolt.org/z/hnTrsceTv