This bug was revelead while using bittorrent.
For filenames started with a dot and two slashes .//
the open_bittorrent_file returned -1 and set errno to EEXIST.
Instead, convert the element pointers inside the comparison functions.
The last argument of qsort() is supposed to be of type
int (*)(const void *, const void *). Previously, comp_links() was
defined to take struct link * instead of const void *, and the type
mismatch was silenced by casting the function pointer to void *.
This was in principle not portable because:
(1) The different pointer types may have different representations.
In a word-oriented machine, the const void * might include a byte
selector while the struct link * might not.
(2) Casting a function pointer to a data pointer can lose bits in some
memory models. Apparently this does not occur in POSIX-conforming
systems though, as dlsym() would fail if it did.
This commit also fixes hits_cmp() and compare_dir_entries(), which
had similar problems. However, I'm leaving alias_compare() in
src/intl/gettext/localealias.c unchanged for now, so as not to diverge
from the GNU version.
I also checked the bsearch() calls but they were all okay, apart from
one that used the alias_compare() mentioned above.
straconcat reads the args with va_arg(ap, const unsigned char *),
and the NULL macro may have the wrong type (e.g. int).
Many places pass string literals of type char * to straconcat. This
is in principle also a violation, but I'm ignoring it for now because
if it becomes a problem with some C implementation, then so will the
use of unsigned char * with printf "%s", which is so widespread in
ELinks that I'm not going to try fixing it now.
