Snippets for abook 0.6.2 from Nix aarch64-darwin

Sourced from https://hydra.nixos.org/log/r4r85bb78wngi1kpvhbcrjnvcqqf1wyd-abook-0.6.2.drv.

./getopt.h:109:13: warning: a function declaration without a prototype is deprecated in all versions of C and is treated as a zero-parameter prototype in C23, conflicting with a previous declaration [-Wdeprecated-non-prototype]
  109 |         extern int getopt();
      |                    ^

filter.c:1961:26: warning: unused variable 'custom_fieldsl' [-Wunused-variable]
 1961 |         abook_field_list *cur, *custom_fieldsl;
      |                                 ^~~~~~~~~~~~~~

getopt.c:217:6: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C23 [-Wdeprecated-non-prototype]
  217 |      my_index(str, chr)
      |      ^

getopt.c:294:6: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C23 [-Wdeprecated-non-prototype]
  294 |      exchange(argv)
      |      ^

getopt.c:356:6: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C23 [-Wdeprecated-non-prototype]
  356 |      _getopt_initialize(argc, argv, optstring)
      |      ^

getopt.c:369:26: warning: passing arguments to 'getenv' without a prototype is deprecated in all versions of C and is not supported in C23 [-Wdeprecated-non-prototype]
  369 |         posixly_correct = getenv("POSIXLY_CORRECT");
      |                                 ^

getopt.c:469:5: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C23 [-Wdeprecated-non-prototype]
  469 |     _getopt_internal(argc, argv, optstring, longopts, longind, long_only)
      |     ^

getopt.c:924:5: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C23 [-Wdeprecated-non-prototype]
  924 |     getopt(argc, argv, optstring)
      |     ^

./getopt.h:109:13: warning: a function declaration without a prototype is deprecated in all versions of C and is treated as a zero-parameter prototype in C23, conflicting with a subsequent definition [-Wdeprecated-non-prototype]
  109 |         extern int getopt();
      |                    ^

getopt1.c:67:5: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C23 [-Wdeprecated-non-prototype]
   67 |     getopt_long(argc, argv, options, long_options, opt_index)
      |     ^

getopt1.c:83:5: warning: a function definition without a prototype is deprecated in all versions of C and is not supported in C23 [-Wdeprecated-non-prototype]
   83 |     getopt_long_only(argc, argv, options, long_options, opt_index)
      |     ^

remap.c:26:9: warning: returning 'const char *' from a function with result type 'char *' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
   26 |         return _("remap key out of range");
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~

ui.c:308:31: warning: array subscript is of type 'char' [-Wchar-subscripts]
  308 |                         helpline[i-1] = remap_table[helpline[i-1]];
      |                                                    ^~~~~~~~~~~~~~