[Fix #1170] Remove the vkill package

Seems it's no longer available on MELPA.

See https://github.com/melpa/melpa/pull/5409 for details.

core/prelude-macos.el

@@ -34,7 +34,7 @@
 
 ;; On macOS Emacs doesn't use the shell PATH if it's not started from
 ;; the shell. Let's fix that:
-(prelude-require-packages '(exec-path-from-shell vkill))
+(prelude-require-packages '(exec-path-from-shell))
 
 (require 'exec-path-from-shell)
 (exec-path-from-shell-initialize)
@@ -42,10 +42,6 @@
 ;; It's all in the Meta
 (setq ns-function-modifier 'hyper)
 
-;; proced-mode doesn't work on macOS so we use vkill instead
-(autoload 'vkill "vkill" nil t)
-(global-set-key (kbd "C-x p") 'vkill)
-
 (defun prelude-swap-meta-and-super ()
   "Swap the mapping of Meta and Super.
 Very useful for people using their Mac with a