libstdc++: check for openat with dirfd in std::filesystem

In the recent patch to check for openat, I missed an occurrence of
dirfd in std::filesystem.

for  libstdc++-v3/ChangeLog

	* src/c++17/fs_dir.cc (dir_and_pathname): Use dirfd if
	_GLIBCXX_HAVE_OPENAT.

(cherry picked from commit 486893b1d325d22d54c1380937943913a7501f91)

diff --git a/libstdc++-v3/src/c++17/fs_dir.cc b/libstdc++-v3/src/c++17/fs_dir.cc
index c67fe76..25b33ba 100644 (file)
--- a/libstdc++-v3/src/c++17/fs_dir.cc
+++ b/libstdc++-v3/src/c++17/fs_dir.cc
@@ -124,7 +124,7 @@ struct fs::_Dir : _Dir_base
   dir_and_pathname() const noexcept
   {
     const fs::path& p = entry.path();
-#if _GLIBCXX_HAVE_DIRFD
+#if _GLIBCXX_HAVE_DIRFD && _GLIBCXX_HAVE_OPENAT
     if (!p.empty())
       return {::dirfd(this->dirp), std::prev(p.end())->c_str()};
 #endif