[libcxx] r285382 - Add __libcpp_version file and __libcpp_library_version function.

[Joerg Sonnenberger via cfe-commits]

On Fri, Oct 28, 2016 at 06:06:50AM -0000, Eric Fiselier via cfe-commits wrote:
> Author: ericwf
> Date: Fri Oct 28 01:06:50 2016
> New Revision: 285382
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=285382&view=rev
> Log:
> Add __libcpp_version file and __libcpp_library_version function.

I really don't see why this is preferable over just checking __config or
the classic approach of including <ciso646> and checking the macros.

Joerg