Pacify --enable-gcc-warnings

Pacify --enable-gcc-warnings

* src/frame.h (x_query_color): Remove redundant extern decl.
* src/ftcrfont.c (ftcrfont_glyph_extents, ftcrfont_list)
(ftcrfont_match, ftcrfont_open, ftcrfont_close)
(ftcrfont_text_extents, ftcrfont_draw):
* src/xterm.c (x_set_window_size_1, *x_color_cells, x_update_end)
(XTframe_up_to_date, x_clear_area1, x_clear_frame)
(x_ins_del_lines, frame_highlight, frame_unhighlight)
(x_new_focus_frame, x_focus_changed, XTframe_rehighlight)
(x_draw_hollow_cursor, x_draw_bar_cursor, x_flush, x_update_begin)
(x_update_window_begin, x_connection_closed)
(x_set_clip_rectangles, x_reset_clip_rectangles, x_fill_rectangle)
(x_draw_rectangle, x_fill_trapezoid_for_relief, x_clear_window)
(*x_gc_get_ext_data, x_extension_initialize)
(x_cr_accumulate_data):
Remove redundant static decl.  Many of these GCC doesn't complain
about, but we might as well clean out the duplication while we're
in the neighborhood.
* src/xterm.c (x_fill_trapezoid_for_relief):
Remove decl of nonexistent function.