[committed] libstdc++: Add comment noting LWG 3617 support

[Jonathan Wakely]

Tested x86_64-linux. Pushed to trunk.

-- >8 --

The resolution was implemented in r14-8752-g6f75149488b74a but I didn't
add the usual _GLIBCXX_RESOLVE_LIB_DEFECTS comment.

libstdc++-v3/ChangeLog:

	* include/bits/std_function.h: Add comment about LWG 3617 being
	supported.
---
 libstdc++-v3/include/bits/std_function.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libstdc++-v3/include/bits/std_function.h b/libstdc++-v3/include/bits/std_function.h
index 79b59466fe9..bb8d8b9306c 100644
--- a/libstdc++-v3/include/bits/std_function.h
+++ b/libstdc++-v3/include/bits/std_function.h
@@ -698,6 +698,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     { using type = _Res(_Args...); };
 
 #if __cpp_explicit_this_parameter >= 202110L
+  // _GLIBCXX_RESOLVE_LIB_DEFECTS
+  // 3617. function/packaged_task deduction guides and deducing this
   template<typename _Res, typename _Tp, bool _Nx, typename... _Args>
     struct __function_guide_helper<_Res (*) (_Tp, _Args...) noexcept(_Nx)>
     { using type = _Res(_Args...); };
-- 
2.45.2