Fix the path on emacs on Mac

init.el

;; fix the PATH variable
(defun set-exec-path-from-shell-PATH ()
  (let ((path-from-shell (shell-command-to-string "$SHELL -i -c 'echo -n $PATH'")))
    (setenv "PATH" path-from-shell)
    (setq exec-path (split-string path-from-shell path-separator))))

(defun set-env-from-shell (envvar)
  (let ((path-from-shell (shell-command-to-string (format "$SHELL -i -c 'echo -n $%s'" envvar))))
    (setenv envvar path-from-shell)))

(if window-system
    (progn
	  (set-exec-path-from-shell-PATH)
	  (set-env-from-shell "GOPATH")
	  (set-env-from-shell "GOROOT")))