[PATCH 2 of 3 V3] color: enable ANSI support on Windows 10

[Matt Harbison]

On Tue, 30 May 2017 22:50:14 -0400, Matt Harbison <mharbison72 at gmail.com>  
wrote:

> # HG changeset patch
> # User Matt Harbison <matt_harbison at yahoo.com>
> # Date 1495506038 14400
> #      Mon May 22 22:20:38 2017 -0400
> # Node ID d0dcc7b57bab42b1e79931ef5cab4ba66a0cc58e
> # Parent  79425b258088af20ae520e24bd60ab471dd62ec4
> color: enable ANSI support on Windows 10

It's not an issue that started with this series, but I just noticed that  
`less` in msys displays '?' files in light blue, whereas normally it is  
pink.

$ PAGER="less -FRX" ../hg st --config color.mode=ansi
# light '?' blue

$ ../hg st --pager=no
# pink '?' files

$ ../hg showconfig | grep color

I don't have access to Windows 10 to see if this series helps fix that  
(with more.com or less.exe).