ob-emacs-lisp: Don't print arguments of post-process arguments to stdout

* lisp/ob-emacs-lisp.el (org-babel-expand-body:emacs-lisp): Do not
print post-processing argument.

It is unclear whether the arguments were printed on purpose.  It might
be useful to do so at times for debugging purposes, but generally they
drown out other messages when a lot of post-processing is being done;
making it harder to spot messages of interest that would otherwise
allow noticing regressions.  This is particularly troublesome when
running `org-babel-execute-buffer' from a Makefile or script.

lisp/ob-emacs-lisp.el

@@ -58,7 +58,7 @@ by `org-edit-src-code'.")
       (format "(let (%s)\n%s\n)"
 	      (mapconcat
 	       (lambda (var)
-		 (format "%S" (print `(,(car var) ',(cdr var)))))
+		 (format "%S" `(,(car var) ',(cdr var))))
 	       vars "\n      ")
 	      body))))