purescript-indentation: remove Emacs 21 work around

We don't support Emacs 21 (it's very old), so no point in keeping it.

Author: Hi-Angel

purescript-indentation.el

@@ -111,13 +111,6 @@
   :group 'purescript-indentation)
 
 
-;; Avoid a global bogus definition (which the original run-time
-;; `defun' made), and support Emacs 21 without the syntax.el add-on.
-(eval-when-compile
-  (unless (fboundp 'syntax-ppss)
-    (defsubst syntax-ppss (&rest pos)
-      (parse-partial-sexp (point-min) (or pos (point))))))
-
 (defconst purescript-indentation-mode-map
   (let ((keymap (make-sparse-keymap)))
     (define-key keymap [?\r] 'purescript-newline-and-indent)