`crypt()` invokes coredump in interpreter.c

[sshine]

On my computer, but not on @gpiedimonte's, crypt() causes a coredump when entering one's password for the first time. (This was discovered in #2.)

The problem lines in interpreter.c are:

1182:strncpy(d->pwd, crypt(arg, d->character->player.name), 10);
1380:strncpy(d->pwd, crypt(arg, d->character->player.name), 10);

crypt() doesn't return a NULL pointer; trying to print its output in gdb gives:

$1 = 0xfffffffff7dd41e0 <error: Cannot access memory at address 0xfffffffff7dd41e0>