testsuite: Fix up g++.dg/reflect/type_trait14.C for -fimplicit-constexpr [PR124844]

The g++.dg/reflect/type_trait14.C test FAILs with -fimplicit-constexpr,
because in that case NLType is actually a literal type rather than
non-literal type and so is structural type too.

Fixed by making sure it is not a literal type even with
-fimplicit-constexpr.

2026-04-10  Jakub Jelinek  <jakub@redhat.com>

	PR c++/124844
	* g++.dg/reflect/type_trait14.C (NLType::~NLType): Move definition out
	of the class.

Reviewed-by: Jason Merrill <jason@redhat.com>

Author: jakubjelinek

gcc/testsuite/g++.dg/reflect/type_trait14.C

@@ -25,8 +25,9 @@ struct NLType {
   NLType () : _M_i(0) { }
   constexpr NLType (int __i) : _M_i(__i) { }
   NLType (const NLType &__other) : _M_i(__other._M_i) { }
-  ~NLType () { _M_i = 0; }
+  ~NLType ();
 };
+NLType::~NLType () { _M_i = 0; }
 
 static_assert (is_structural_type (^^int));
 static_assert (is_structural_type (^^float));