The standard streams `stdaux' and `stdprn' are defined incorrectly in
src/libc/ansi/stdio/stdprn.c and stdaux.c.  stdaux should use file
handle 3 and stdprn should use handle 4.  The library defines them
the other way around.

Obvious: change the file handle for stdprn to 4 and file handle for
stdaux to 3.