bug#27840: 26.0.50; vc-git-grep stopped working on git master

[Dmitry Gutov]

On 8/3/17 6:09 AM, npostavs@users.sourceforge.net wrote:
> * lisp/progmodes/grep.el (grep--regexp-alist-column)
> (grep--regexp-alist-bin-matcher, grep-with-null-regexp-alist)
> (grep-fallback-regexp-alist): Remove.
> (grep-regexp-alist): Recombine their contents here.
> (grep-mode):
> * lisp/progmodes/xref.el (xref-collect-matches): Use the variable
> `grep-regexp-alist' rather than the function.

Also semantic/symref/grep.el. I fixed it before in a separate patch, but 
let's keep this update all together.