Emacs: Toggle modeline icons depending on GUI or TUI.

Only globally possible at the moment.
<https://github.com/seagle0128/doom-modeline/issues/375>

init.d/basics/appearance.el

@@ -1,6 +1,6 @@
 ;;; appearance.el --- Configure appearance. -*- lexical-binding: t; -*-
 
-;; Time-stamp: <2020-11-29T10:54:00+0100>
+;; Time-stamp: <2020-11-30T09:58:13+0100>
 
 ;;; Commentary:
 
@@ -114,7 +114,12 @@
            (doom-modeline-buffer-file-name-style 'truncate-all)
            (mode-line-percent-position nil)       ; Don't display percentage.
            (doom-modeline-buffer-state-icon nil)) ; Don't display save icon.
-  :hook (after-init . doom-modeline-mode))
+  :hook ((after-init . doom-modeline-mode)
+         ;; <https://github.com/seagle0128/doom-modeline/issues/375>
+         (server-after-make-frame . (lambda ()
+                                      (customize-set-variable
+                                       'doom-modeline-icon
+                                       (display-graphic-p))))))
 
 ;; Show line numbers on the left side of the buffer.
 (use-package display-line-numbers