Add the setup_fail_codec label and jump to it if an error occurs once the
codec has been opened. In the raw input codepath, don't use this label until
the file is properly opened, as it also closes the fd and frees the raw
buffer.
This also fixes a file descriptor leak in the case where an error happened
after the file was opened in the raw input codepath.
lseek() returns an off_t and not an int, using an int to store and
test the return value means we'll error out when the position in the file
gets past INT_MAX.
Try to be a bit more strict about integer types, use off_t or int64_t for
file size and file offsets.
Replace safe_ato*() by safe_atoi32() and safe_atoi64(), fix integer types
at call sites to match.
