[Bug libstdc++/86756] Don't define __cpp_lib_filesystem unless --enable-libstdcxx-filesystem-ts

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86756

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The C++17 std::filesystem library is now supported unconditionally, so it's
correct to define __cpp_lib_filesystem unconditionally. So this is fixed.