Making mairix work with mbox files over 2GB.

[viric]

Should fix #12

I pick the patch proposed there by @taviso, but I improve it so it
fixes not only the db update, but also db search (tested with mairix -x).

[viric]

Oh I just noticed this: https://github.com/rc0/mairix/pull/16/files

[martinetd]

This is included in nixpkgs and breaks build with gcc 14, because some arguments no longer match function prototype for example:

search.c:1351:74: error: passing argument 3 of 'create_ro_mapping' from incompatible pointer type [-Wincompatible-pointer-types]
 1351 |                 create_ro_mapping(db->data + db->path_offsets[i], &data, &len);
      |                                                                          ^~~~
      |                                                                          |
      |                                                                          int *
In file included from search.c:44:
mairix.h:336:76: note: expected 'size_t *' {aka 'long unsigned int *'} but argument is of type 'int *'
  336 | void create_ro_mapping(const char *filename, unsigned char **data, size_t *len);
      |                                                                    ~~~~~~~~^~~
search.c:1369:60: error: passing argument 5 of 'get_validated_mbox_msg' from incompatible pointer type [-Wincompatible-pointer-types]
 1369 |                 get_validated_mbox_msg(db, i, &mbi, &data, &mbox_len, &start, &msg_len);
      |                                                            ^~~~~~~~~
      |                                                            |
      |                                                            int *
search.c:722:71: note: expected 'size_t *' {aka 'long unsigned int *'} but argument is of type 'int *'
  722 |                                    unsigned char **mbox_data, size_t *mbox_len,
      |                                                               ~~~~~~~~^~~~~~~~
search.c:1369:79: error: passing argument 7 of 'get_validated_mbox_msg' from incompatible pointer type [-Wincompatible-pointer-types]
 1369 |                 get_validated_mbox_msg(db, i, &mbi, &data, &mbox_len, &start, &msg_len);
      |                                                                               ^~~~~~~~
      |                                                                               |
      |                                                                               int *
search.c:723:71: note: expected 'size_t *' {aka 'long unsigned int *'} but argument is of type 'int *'
  723 |                                    unsigned char **msg_data,  size_t *msg_len)
      |                                                               ~~~~~~~~^~~~~~~

(probably ought to open that error as a new issue in nixpkgs but you're the one that added mairix there, and your packages have been orphaned, so here is as good as anything else... I'll drop the package from my machine for now)