Fix emplace for types with a deleted move constructor (in the not trivially destructible case)

test/variant_emplace_type.cpp

@@ -61,6 +61,11 @@ struct Y1
 {
 };
 
+struct Y2
+{
+    ~Y2() {}
+};
+
 struct Guard
 {
     explicit Guard(int) {}
@@ -180,5 +185,10 @@ int main()
         v.emplace<Guard>( 1 );
     }
 
+    {
+        variant<Y2, Guard> v;
+        v.emplace<Guard>( 1 );
+    }
+
     return boost::report_errors();
 }