[gcc r13-9716] libstdc++: Fix backported test [PR112490]

[Patrick Palka]

https://gcc.gnu.org/g:c923901d9cd16b4105312a3319c245cbcb02bf83

commit r13-9716-gc923901d9cd16b4105312a3319c245cbcb02bf83
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue May 27 17:49:30 2025 -0400

    libstdc++: Fix backported test [PR112490]
    
    On the 13 branch and older, C++ >= 20 tests need an explicit dg-options
    directive specifying the -std flag, otherwise they won't run by default.
    
            PR libstdc++/112490
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/24_iterators/const_iterator/112490.cc: Add
            dg-options directive.

Diff:
---
 libstdc++-v3/testsuite/24_iterators/const_iterator/112490.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libstdc++-v3/testsuite/24_iterators/const_iterator/112490.cc b/libstdc++-v3/testsuite/24_iterators/const_iterator/112490.cc
index 9bb154847cff..e6e74eb675d4 100644
--- a/libstdc++-v3/testsuite/24_iterators/const_iterator/112490.cc
+++ b/libstdc++-v3/testsuite/24_iterators/const_iterator/112490.cc
@@ -1,3 +1,4 @@
+// { dg-options "-std=gnu++23" }
 // { dg-do compile { target c++23 } }
 
 // PR libstdc++/112490 - infinite meta error in