[Bug libstdc++/59177] steady_clock::now() and system_clock::now do not use the vdso (and are therefore very slow)

[luto at mit dot edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59177

--- Comment #9 from Andy Lutomirski <luto at mit dot edu> ---
Given that this is C++11-only, it's already fixed on trunk, it's only a
performance issue (as opposed to correctness), and it's more complicated than
just changing the default, I won't argue for a backport.

>From my perspective, feel free to close this.