Use temporary files in lto

[Rafael Espíndola via llvm-commits]

On 28 April 2016 at 20:08, Rui Ueyama <ruiu at google.com> wrote:
> It is actually harder than I thought as I have never built ELF executables
> with LTO on Windows. Did anyone do that before?
>

I uploaded a --reproduce of llvm-as to
https://drive.google.com/open?id=0B7iRtublysV6NWNqS3VHOVEydmc.

It should run under windows.

Cheers,
Rafael