bug#9408: 23.3; vc-git-grep doesn't link to files when git grep uses colour

[Juri Linkov]

> I built revision 105661, then ran $ src/emacs -Q but I did not get search
> highlighting with vc-git-grep. File name highlighting works fine. My git
> version is:
>
> $ git --version
> git version 1.7.6.1

My git version is 1.7.1 and I get search highlighting when I enable
colour for git with: $ git config --global color.ui auto
and when `git grep' runs without "--no-color".