.emacs: Add missing `require`
.emacs: Add missing `require`

`vvv/grep` uses `string-trim-right` and `string-empty-p` functions.
Those functions are provided by `subr-x` module, which is not imported
by default.

See also http://ergoemacs.org/emacs/elisp_trim_string.html

vvv/dotfiles,vvv/dotfiles,vvv/dotfiles,vvv/dotfiles