[PATCH] Allow using ANSI escape sequences on Windows

[Nico Rieck]

On 02.09.2013 20:45, Chandler Carruth wrote:
> On nix-ish platforms, -fcolor-diagnostics actually enables colors even for
> pipes, and so works with Ninja or other build systems that use pipes. Is
> the problem that you need to switch from console APIs to produce the colors
> to ANSI escapes?

Exactly.

> How about a -fansi-escape-colors or some such?
>
> Generally, I'd like to avoid the use of the environment variables. Command
> line switches and such are easier to test, set, and audit in most cases.

I initially opted to use an environment variable to keep the impact 
small. But if you think a command line switch would be better, that's 
fine with me and I'll rewrite this.

-Nico