Fix test failures with trunk clang

- Make the consteval constructor for the zero type be noexcept
- Don't expect three-way comparison of 0 against a comparison category
  to fail

libcxx/include/compare

@@ -156,7 +156,7 @@ enum class _LIBCPP_ENUM_VIS _NCmpResult : signed char {
 
 struct _CmpUnspecifiedParam {
   _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEVAL
-  _CmpUnspecifiedParam(int _CmpUnspecifiedParam::*) {}
+  _CmpUnspecifiedParam(int _CmpUnspecifiedParam::*) noexcept {}
 
   template<typename _Tp, typename = _VSTD::enable_if_t<!_VSTD::is_same_v<_Tp, int>>>
   _CmpUnspecifiedParam(_Tp) = delete;

libcxx/test/std/language.support/cmp/cmp.categories.pre/zero_type.verify.cpp

@@ -46,9 +46,9 @@ void test_category(T v) {
   void(0 > v);
   void(v >= 0);
   void(0 >= v);
-#ifndef _LIBCPP_HAS_NO_THREE_WAY_COMPARISON
-  void(v <=> 0); // expected-error 3 {{}}
-  void(0 <=> v); // expected-error 3 {{}}
+#ifndef _LIBCPP_HAS_NO_SPACESHIP_OPERATOR
+  void(v <=> 0);
+  void(0 <=> v);
 #endif
 }