Fix a printf format string signedness warning

[sulix]

gcc 13.2 outputs several warnings for mismatched printf format strings, such as:

/home/david/Development/julius/test/sav/sav_compare.c: In function ‘compare_part’: /home/david/Development/julius/test/sav/sav_compare.c:522:45: warning: format ‘%X’ expects argument of type ‘unsigned int’, but argument 3 has type ‘int’ [-Wformat=]
  522 |                 printf("record %d offset 0x%X", i / save_game_parts[index].record_length, i % save_game_parts[index].record_length);
      |                                            ~^                                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                             |                                               |
      |                                             unsigned int                                    int
      |                                            %X

This patch doesn't fix all of them, but does fix the simple ones. The more complicated ones include signedness issues with '%X' in the sav_compare test, which would either require a rework of the signedness of a whole bunch of code, or a hacky cast:

/home/david/Development/julius/test/sav/sav_compare.c: In function ‘compare_part’:
/home/david/Development/julius/test/sav/sav_compare.c:522:45: warning: format ‘%X’ expects argument of type ‘unsigned int’, but argument 3 has type ‘int’ [-Wformat=]
  522 |                 printf("record %d offset 0x%X", i / save_game_parts[index].record_length, i % save_game_parts[index].record_length);
      |                                            ~^                                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                             |                                               |
      |                                             unsigned int                                    int
      |                                            %X

There's also a warning about the format string not being a literal in the screenshot code, which would probably require a more clever fix:

/home/david/Development/julius/src/graphics/screenshot.c: In function ‘generate_filename’:
/home/david/Development/julius/src/graphics/screenshot.c:103:55: warning: format not a string literal, format string not checked [-Wformat-nonliteral]
  103 |     strftime(filename, FILE_NAME_MAX, filename_formats[city_screenshot], loctime);
      |                                       ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~

All of these are pretty harmless, so it's not particularly important that all (or any) of them actually get fixed. But it's nice to remove a warning if we can. :-)

[bvschaik]

But it's nice to remove a warning if we can. :-)

Exactly :-)

The ones in sav_compare are not important since that code is only used in tests. I'm not sure how we can fix the screenshot one. And the two you fixed in this PR are good to fix indeed. Thanks!