Fix elisp-byte-compile-buffer requirements

* lisp/progmodes/elisp-mode.el (elisp-byte-compile-buffer):
Require bytecomp so that byte-compile-dest-file-function is
defined.  (The byte compiler didn't catch this, because it's
defined in bytecomp.)

lisp/progmodes/elisp-mode.el

@@ -2223,6 +2223,7 @@ interactively, this is the prefix argument."
   (interactive "P")
   (let ((bfn buffer-file-name)
         file elc)
+    (require 'bytecomp)
     (unwind-protect
         (progn
           (setq file (make-temp-file "compile" nil ".el")