* process.c (ifflag_def): Make flag_sym constant.

* process.c (ifflag_def): Make flag_sym constant.
(Fnetwork_interface_info): Use a constant pointer.
(ifflag_table):
* xfns.c (cursor_bits):
* xdisp.c (power_letter):
* termcap.c (speeds, esctab):
* sysdep.c (baud_convert):
* keyboard.c (lispy_accent_codes, modifier_names):
* image.c (xbm_format, xpm_format, pbm_format, png_format)
(jpeg_format, tiff_format, gif_format, svg_format)
(interlace_start, interlace_increment, gs_format):
* gtkutil.c (separator_names):
* fringe.c (swap_nibble):
* fns.c (base64_value_to_char, base64_char_to_value):
* fileio.c (make_temp_name_tbl):
* coding.c (suffixes): Make constant.