* xterm.c: Fix problems found by static analysis with other toolkits.
(toolkit_scroll_bar_interaction): Define and use only if USE_X_TOOLKIT.
(x_dispatch_event): Declare static only if !USE_GTK && USE_X_TOOLKIT.
Define if USE_GTK || (HAVE_MENUS && USE_X_TOOLKIT); USE_MOTIF need
not be part of this test.
(SET_SAVED_BUTTON_EVENT): Define only if USE_X_TOOLKIT || USE_GTK.
* xterm.h (x_dispatch_event): Use USE_GTK, not USE_MOTIF, when testing
whether to declare.
* xterm.c, xterm.h (x_mouse_leave): Bring this function back, but only if
defined HAVE_MENUS && !defined USE_X_TOOLKIT && !defined USE_GTK.