emacs: use ninja-mode

emacs/init.el

@@ -119,6 +119,9 @@
   :hook ((markdown-mode . flyspell-mode))
   :mode (("\\.mdwn\\'" . markdown-mode)))
 
+(use-package ninja-mode
+  :ensure t)
+
 (use-package ruby-mode
   :init
   (defvaralias 'ruby-indent-level 'tab-width)