* window.h (struct window): Convert scroll_bar_width

* window.h (struct window): Convert scroll_bar_width
from Lisp_Object to integer.  Adjust comment.
(WINDOW_CONFIG_SCROLL_BAR_WIDTH, WINDOW_CONFIG_SCROLL_BAR_COLS):
Adjust users.
* window.c (wset_scroll_bar_width): Remove.
(make_window): Initialize scroll_bar_width.
(Fsplit_window_internal): Use direct assignment.
(Fset_window_configuration, save_window_save):
Convert Lisp_Object to integer and back where appropriate.
(Fset_window_scroll_bars): Adjust user.  Return t if any scroll
bar was actually changed, and mention this in docstring.