Clean up PGTK code some more

Clean up PGTK code some more

* src/pgtkterm.c (x_alloc_lighter_color): Simplify.  Do not try
to "allocate" colors, remove unused flag and impossible return
value.
(pgtk_clear_frame): Remove unused code from NS port and remove
incorrect workaround for now-fixed double buffering.
(pgtk_make_frame_visible_wait_for_map_event_cb)
(x_clear_glyph_string_rect, x_draw_glyph_string_background)
(x_draw_glyph_string_foreground)
(x_draw_composite_glyph_string_foreground)
(x_draw_glyphless_glyph_string_foreground)
(x_fill_trapezoid_for_relief, x_erase_corners_for_relief)
(pgtk_setup_relief_color, x_draw_relief_rect, x_draw_box_rect)
(x_draw_glyph_string_box, x_get_scale_factor)
(x_draw_horizontal_wave, pgtk_draw_horizontal_wave)
(x_draw_underwave, x_draw_image_relief)
(x_draw_glyph_string_bg_rect, x_cr_draw_image)
(x_draw_image_foreground, x_draw_image_glyph_string)
(x_draw_stretch_glyph_string, pgtk_draw_glyph_string)
(x_draw_hollow_cursor, x_draw_bar_cursor, pgtk_draw_window_cursor)
(pgtk_cr_draw_image, pgtk_draw_fringe_bitmap, hourglass_cb)
(pgtk_show_hourglass, pgtk_redraw_scroll_bars, pgtk_flash)
(x_create_toolkit_scroll_bar)
(x_create_horizontal_toolkit_scroll_bar, x_scroll_bar_create)
(x_scroll_bar_remove, pgtk_set_vertical_scroll_bar)
(pgtk_set_horizontal_scroll_bar, pgtk_judge_scroll_bars)
(x_new_focus_frame, x_focus_changed, enter_notify_event)
(leave_notify_event, focus_in_event, focus_out_event)
(pgtk_cr_accumulate_data): Clean up coding style, rename
functions copied over from X and modified, and remove duplicate
definition of at least one function.