Fix problems found by static checking --with-ns

Fix problems found by static checking --with-ns

This is for Fedora 24 when configured with --enable-gcc-warnings.
Although it does not fix all the problems, it fixes many of them.
* src/frame.c (XParseGeometry):
* src/nsterm.m (mouseDown:):
Mark locals with UNINIT to pacify --enable-gcc-warnings.
* src/image.c (PIX_MASK_DRAW, DefaultDepthOfScreen):
Remove unused macros.
(slurp_file xbm_scan, xbm_read_bitmap_data, xbm_load_image)
(xbm_file_p, xbm_load, xpm_scan, xpm_make_color_table_v)
(xpm_put_color_table_v, xpm_get_color_table_v)
(xpm_make_color_table_h, xpm_put_color_table_h)
(xpm_get_color_table_h, xpm_load_image, xpm_load)
(pbm_next_char, pbm_scan_number, pbm_load, svg_load)
(svg_load_image):
* src/nsfns.m (x_get_string_resource):
* src/nsimage.m (ns_image_from_XBM):
Fix pointer signedness problems.
* src/image.c (xpm_load_image, x_build_heuristic_mask, pbm_load)
(imagemagick_load_image): Omit unused locals.
* src/nsfns.m (ns_send_types, ns_return_types, ns_drag_types)
(Fx_open_connection):
* src/nsfont.m (ns_antialias_threshold):
Move extern decl to nsterm.h so it can be checked.
* src/nsmenu.m (svcsMenu, dockMenu):
Move to the only file that uses them, so they can be static.
* src/nsterm.h (find_and_call_menu_selection):
* src/nsterm.m (x_set_frame_alpha):
Omit duplicate decls.
* src/nsterm.h (ns_dump_glyphstring): Mark as EXTERNALLY_VISIBLE.
* src/nsfns.m (ns_tooltip, ns_display_info_for_name)
(ns_set_name_as_filename, x_set_menu_bar_lines)
(x_set_tool_bar_lines, x_set_internal_border_width):
* src/nsterm.m (ns_drag_types, ns_draw_text_decoration):
Now static.
* src/nsfns.m (ns_lisp_to_cursor_type, ns_cursor_type_to_lisp):
* src/nsterm.m (ns_free_indexed_color, ns_color_to_lisp):
Remove; unused.
* src/nsfont.m (ns_dump_glyphstring):
* src/nsterm.m (hide_bell, ns_get_color, ns_color_to_lisp)
(ns_clear_frame, keyDown:):
Fix signedness problem with printf arg.
* src/nsterm.h (ns_input_events, ns_finish_events):
* src/nsterm.m (ns_finish_events, hide_bell):
Prototype the decls.
* src/nsterm.m (NSMenuDidBeginTrackingNotification):
Omit unnecessary decl.
(dockMenu):
(mainMenu) [NS_IMPL_COCOA]: Now static, and in this file.
(ns_dumpglyphs_box_or_relief, changeFont:, initFrameFromEmacs:)
(toggleFullScreen:): Use FACE_FROM_ID instead of
FACE_FROM_ID_OR_NULL in contexts where the caller expects the
result to be non-null.
(applicationShouldTerminate:): Fix misleading indentation.