bug#16526: 24.3.50; scroll-conservatively & c-mode regression

[martin rudalics]

With current trunk and emacs -Q evaluating the following form takes more
than two minutes here with builds on Windows and GNU/Linux:

(progn
  (setq scroll-conservatively 101)
  (find-file (concat source-directory "src/xdisp.c"))
  (end-of-buffer)
  (sit-for 3)
  (beginning-of-buffer))

It used to take about 10 seconds before revision 116070.

martin