c++: __has_builtin gives the wrong answer [PR106759]

We've supported __is_nothrow_constructible since r11-4386, but
names_builtin_p didn't know about it, so it gave the wrong answer for
 #if __has_builtin(__is_nothrow_constructible)
 ...
 #endif

I've tested all C++-only built-ins and only two were missing.

	PR c++/106759

gcc/cp/ChangeLog:

	* cp-objcp-common.cc (names_builtin_p): Handle RID_IS_NOTHROW_ASSIGNABLE
	and RID_IS_NOTHROW_CONSTRUCTIBLE.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/has-builtin-1.C: New test.

gcc/cp/cp-objcp-common.cc

@@ -460,6 +460,8 @@ names_builtin_p (const char *name)
     case RID_IS_UNION:
     case RID_IS_ASSIGNABLE:
     case RID_IS_CONSTRUCTIBLE:
+    case RID_IS_NOTHROW_ASSIGNABLE:
+    case RID_IS_NOTHROW_CONSTRUCTIBLE:
     case RID_UNDERLYING_TYPE:
     case RID_REF_CONSTRUCTS_FROM_TEMPORARY:
     case RID_REF_CONVERTS_FROM_TEMPORARY:

gcc/testsuite/g++.dg/ext/has-builtin-1.C

@@ -0,0 +1,133 @@
+// PR c++/106759
+// { dg-do compile }
+// Verify that __has_builtin gives the correct answer for C++ built-ins.
+
+#if !__has_builtin (__builtin_addressof)
+# error "__has_builtin (__builtin_addressof) failed"
+#endif
+#if !__has_builtin (__builtin_bit_cast)
+# error "__has_builtin (__builtin_bit_cast) failed"
+#endif
+#if !__has_builtin (__builtin_launder)
+# error "__has_builtin (__builtin_launder) failed"
+#endif
+#if !__has_builtin (__has_nothrow_assign)
+# error "__has_builtin (__has_nothrow_assign) failed"
+#endif
+#if !__has_builtin (__has_nothrow_constructor)
+# error "__has_builtin (__has_nothrow_constructor) failed"
+#endif
+#if !__has_builtin (__has_nothrow_copy)
+# error "__has_builtin (__has_nothrow_copy) failed"
+#endif
+#if !__has_builtin (__has_trivial_assign)
+# error "__has_builtin (__has_trivial_assign) failed"
+#endif
+#if !__has_builtin (__has_trivial_constructor)
+# error "__has_builtin (__has_trivial_constructor) failed"
+#endif
+#if !__has_builtin (__has_trivial_copy)
+# error "__has_builtin (__has_trivial_copy) failed"
+#endif
+#if !__has_builtin (__has_trivial_destructor)
+# error "__has_builtin (__has_trivial_destructor) failed"
+#endif
+#if !__has_builtin (__has_unique_object_representations)
+# error "__has_builtin (__has_unique_object_representations) failed"
+#endif
+#if !__has_builtin (__has_virtual_destructor)
+# error "__has_builtin (__has_virtual_destructor) failed"
+#endif
+#if !__has_builtin (__is_abstract)
+# error "__has_builtin (__is_abstract) failed"
+#endif
+#if !__has_builtin (__is_aggregate)
+# error "__has_builtin (__is_aggregate) failed"
+#endif
+#if !__has_builtin (__is_base_of)
+# error "__has_builtin (__is_base_of) failed"
+#endif
+#if !__has_builtin (__is_class)
+# error "__has_builtin (__is_class) failed"
+#endif
+#if !__has_builtin (__is_empty)
+# error "__has_builtin (__is_empty) failed"
+#endif
+#if !__has_builtin (__is_enum)
+# error "__has_builtin (__is_enum) failed"
+#endif
+#if !__has_builtin (__is_final)
+# error "__has_builtin (__is_final) failed"
+#endif
+#if !__has_builtin (__is_layout_compatible)
+# error "__has_builtin (__is_layout_compatible) failed"
+#endif
+#if !__has_builtin (__is_literal_type)
+# error "__has_builtin (__is_literal_type) failed"
+#endif
+#if !__has_builtin (__is_pointer_interconvertible_base_of)
+# error "__has_builtin (__is_pointer_interconvertible_base_of) failed"
+#endif
+#if !__has_builtin (__is_pod)
+# error "__has_builtin (__is_pod) failed"
+#endif
+#if !__has_builtin (__is_polymorphic)
+# error "__has_builtin (__is_polymorphic) failed"
+#endif
+#if !__has_builtin (__is_same)
+# error "__has_builtin (__is_same) failed"
+#endif
+#if !__has_builtin (__is_same_as)
+# error "__has_builtin (__is_same_as) failed"
+#endif
+#if !__has_builtin (__is_standard_layout)
+# error "__has_builtin (__is_standard_layout) failed"
+#endif
+#if !__has_builtin (__is_trivial)
+# error "__has_builtin (__is_trivial) failed"
+#endif
+#if !__has_builtin (__is_trivially_assignable)
+# error "__has_builtin (__is_trivially_assignable) failed"
+#endif
+#if !__has_builtin (__is_trivially_constructible)
+# error "__has_builtin (__is_trivially_constructible) failed"
+#endif
+#if !__has_builtin (__is_trivially_copyable)
+# error "__has_builtin (__is_trivially_copyable) failed"
+#endif
+#if !__has_builtin (__is_union)
+# error "__has_builtin (__is_union) failed"
+#endif
+#if !__has_builtin (__underlying_type)
+# error "__has_builtin (__underlying_type) failed"
+#endif
+#if !__has_builtin (__is_assignable)
+# error "__has_builtin (__is_assignable) failed"
+#endif
+#if !__has_builtin (__is_constructible)
+# error "__has_builtin (__is_constructible) failed"
+#endif
+#if !__has_builtin (__is_nothrow_assignable)
+# error "__has_builtin (__is_nothrow_assignable) failed"
+#endif
+#if !__has_builtin (__is_nothrow_constructible)
+# error "__has_builtin (__is_nothrow_constructible) failed"
+#endif
+#if !__has_builtin (__reference_constructs_from_temporary)
+# error "__has_builtin (__reference_constructs_from_temporary) failed"
+#endif
+#if !__has_builtin (__reference_converts_from_temporary)
+# error "__has_builtin (__reference_converts_from_temporary) failed"
+#endif
+#if !__has_builtin (__builtin_is_constant_evaluated)
+# error "__has_builtin (__builtin_is_constant_evaluated) failed"
+#endif
+#if !__has_builtin (__builtin_source_location)
+# error "__has_builtin (__builtin_source_location) failed"
+#endif
+#if !__has_builtin (__builtin_is_corresponding_member)
+# error "__has_builtin (__builtin_is_corresponding_member) failed"
+#endif
+#if !__has_builtin (__builtin_is_pointer_interconvertible_with_class)
+# error "__has_builtin (__builtin_is_pointer_interconvertible_with_class) failed"
+#endif