[emacs support] add dir-local: swift-basic-offset

Author: Dave Abrahams

.dir-locals.el

@@ -37,16 +37,16 @@
  (c++-mode
   (whitespace-style . (face lines indentation:space))
   (eval . (whitespace-mode)))
- (swift-mode
-  (whitespace-style . (face lines indentation:space))
-  (eval . (whitespace-mode)))
  (objc-mode
   (whitespace-style . (face lines indentation:space))
   (eval . (whitespace-mode)))
  (c-mode
   (whitespace-style . (face lines indentation:space))
   (eval . (whitespace-mode)))
  (swift-mode
+  (whitespace-style . (face lines indentation:space))
+  (eval . (whitespace-mode))
+  (swift-basic-offset . 2)
   (tab-always-indent . t)))
 
 ;; Local Variables: