Fix failed startup when resizing.

From http://debbugs.gnu.org/cgi/bugreport.cgi?bug=23369
and will hopefully be in the next emacs upstream version.

diff -u -r ../emacs-25.0.93/lisp/window.el ./lisp/window.el
--- ../emacs-25.0.93/lisp/window.el	2016-04-22 08:17:00.000000000 -0400
+++ ./lisp/window.el	2016-04-28 08:44:26.318178636 -0400
@@ -8520,6 +8520,7 @@
 displaying that processes's buffer."
   (let ((processes (process-list))
         (process-windows nil))
+   (when processes
     (walk-windows
      (lambda (window)
        (let ((buffer (window-buffer window))
@@ -8538,7 +8539,7 @@
                         nil)
                     (setf iter (cdr iter)))))))
      1 t)
-    process-windows))
+    process-windows)))
 
 (defun window--adjust-process-windows ()
   "Update process window sizes to match the current window configuration."