Cleanups to PGTK code

Cleanups to PGTK code

* src/pgtkfns.c (pgtk_explicitly_set_name, pgtk_set_tab_bar_lines)
(pgtk_change_tab_bar_height, pgtk_set_child_frame_border_width)
(pgtk_set_internal_border_width, pgtk_set_cursor_type)
(pgtk_set_mouse_color, pgtk_set_override_redirect, xg_set_icon)
(pgtk_frame_parm_handlers, Fpgtk_set_monitor_scale_factor)
(pgtk_set_scroll_bar_default_width, pgtk_get_focus_frame)
(pgtk_hide_tip, Fx_show_tip, Fx_hide_tip, frame_geometry)
(syms_of_pgtkfns): Clean up coding style and delete incorrect
comments that mostly duplicate what is in xfns.c, and fix
comment coding style.  Also rename functions from `x_' to
`pgtk_'.

* src/pgtkterm.c (pgtk_setup_relief_colors): Fix relief caching
with new flag.
(pgtk_draw_relief_rect, flip_cr_context, pgtk_wait_for_map_event)
(pgtk_make_frame_visible, pgtk_make_frame_invisible)
(pgtk_set_parent_frame, pgtk_draw_glyph_string_foreground)
(pgtk_draw_composite_glyph_string_foreground)
(pgtk_draw_glyphless_glyph_string_foreground)
(pgtk_set_clip_rectangles, pgtk_draw_glyph_string_bg_rect)
(pgtk_draw_image_foreground, pgtk_draw_image_glyph_string)
(pgtk_draw_stretch_glyph_string, pgtk_draw_glyph_string)
(pgtk_copy_bits, pgtk_bitmap_icon, pgtk_define_fringe_bitmap)
(pgtk_show_hourglass, pgtk_flash, pgtk_send_scroll_bar_event)
(pgtk_free_pixmap, set_opacity_recursively, frame_highlight)
(frame_unhighlight, pgtk_toggle_invisible_pointer)
(pgtk_create_terminal, pgtk_window_is_of_frame_recursive)
(pgtk_window_is_of_frame, pgtk_any_window_to_frame)
(pgtk_handle_draw, size_allocate, pgtk_enqueue_string)
(key_press_event, motion_notify_event): Fix coding style and
some minor bugs.

* src/pgtkterm.h (struct pgtk_output): New field for tracking
relief color status, update prototypes.