-Wdeprecated-literal-operator from clang++-20 for 'operator"" _c' (i.e. with space)

[MichaelChirico]

config/test/boost_no_cxx11_user_lit.ipp

Lines 50 to 55 in 404c783

	my_literal operator "" _suf1(unsigned long long v)
	{
	return my_literal(v);
	}
	template <char...PACK>
	my_literal operator "" _bin()

The fix can be trivial, but I think there's some back-compatibility considerations I lack the context to adjudicate, see sister issues e.g.

boostorg/hana#521