PR libstdc++/86603 Move __cpp_lib_list_remove_return_type macro

This should only be defined for C++2a not C++17.

	PR libstdc++/86603
	* include/std/version: Move __cpp_lib_list_remove_return_type macro.

From-SVN: r262902

libstdc++-v3/ChangeLog

+2018-07-20  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/86603
+	* include/std/version: Move __cpp_lib_list_remove_return_type macro.
+
 2018-07-19  Jonathan Wakely  <jwakely@redhat.com>
 
 	* include/std/type_traits (__is_member_object_pointer_helper): Use

libstdc++-v3/include/std/version

@@ -105,7 +105,6 @@
 #define __cpp_lib_is_swappable 201603
 #define __cpp_lib_launder 201606
 #define __cpp_lib_lcm 201606
-#define __cpp_lib_list_remove_return_type 201806L
 #define __cpp_lib_logical_traits 201510
 #define __cpp_lib_make_from_tuple 201606
 #define __cpp_lib_map_insertion 201411
@@ -127,6 +126,7 @@
 
 #if __cplusplus > 201703L
 // c++2a
+#define __cpp_lib_list_remove_return_type 201806L
 #endif // C++2a
 #endif // C++17
 #endif // C++14