[PATCH] Disable use of std::call_once on OpenBSD with libstdc++

[Joerg Sonnenberger via llvm-commits]

On Sun, Oct 30, 2016 at 01:26:35AM -0500, Hal Finkel via llvm-commits wrote:
> > Any further comment? LGTM?
> 
> To be clear, the change in behavior for PPC is that we were never using
> std::call_once on PPC, but with this change, we'll use std::call_once
> with libc++ but not otherwise?

Correct. LGTM.

Joerg