If the current character is a line break character, it cannot be a tab
or space character, so we would always fail with an invalid sequence
error. Obviously, these `scan_stat == 4` conditions are meant to be
exclusive.
Furthermore, if `in_pp == NULL || in_left_p == NULL` is true, we hit a
segfault if we are not returning right away. Obviously, the additional
constraints don't make sense, so we remove them.
Christoph M. Becker
12c59f6660