Fix scroll bar handling for non-toolkit builds.

Fix scroll bar handling for non-toolkit builds.

* frame.h (FRAME_HAS_HORIZONTAL_SCROLL_BARS): Condition
correctly according to toolkit used.
* frame.c (make_initial_frame, make_terminal_frame)
(x_set_horizontal_scroll_bars, x_set_scroll_bar_height)
(Vdefault_frame_horizontal_scroll_bars): Correctly condition
assignments according to presence of toolkit scrollbars.
* window.h (WINDOW_HAS_HORIZONTAL_SCROLL_BAR): Condition
correctly according to toolkit used.
* window.c (set_window_scroll_bars): Set horizontal scroll bar
only if toolkit supports it.
* w32term.c (w32_redeem_scroll_bar): Always redeem scroll bar if
present.
* xterm.c (x_scroll_bar_create): Initialize horizontal slot for
non-toolkit builds.
(XTredeem_scroll_bar): Always redeem scroll bar if present.