[PATCH] Disable buffering for raw_null_ostream()

[Duncan P. N. Exon Smith]

> On 2015-Jun-30, at 22:40, Mehdi AMINI <mehdi.amini at apple.com> wrote:
> 
> Hi rafael,
> 
> There is no need to buffer the nulls() output.
> Moreover it kept a shared buffer, and made using nulls() not possible
> in a multi-threaded environment.
> 
> http://reviews.llvm.org/D10861
> 
> Files:
>  include/llvm/Support/raw_ostream.h
> 
> Index: include/llvm/Support/raw_ostream.h
> ===================================================================
> --- include/llvm/Support/raw_ostream.h
> +++ include/llvm/Support/raw_ostream.h
> @@ -530,7 +530,7 @@
>   uint64_t current_pos() const override;
> 
> public:
> -  explicit raw_null_ostream() {}
> +  explicit raw_null_ostream() : raw_pwrite_stream(true) {}

Can you document the `true` here?

    : raw_pwrite_stream(/* Unbuffered */ true) {}

Otherwise, LGTM.

>   ~raw_null_ostream() override;
> };