Latest 4.3.0-dev infinite-loops in Y0*.ztst

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

At first I thought the problem was with ptyread(), but in fact it appears
that the process running on the PTY is printing either an infinite, or at
least a very long, string of identical characters which are then read and
tested one by one with pattry() in ptyread() by the PTY master.

I've verified that this does NOT have anything to do with the complist.c
patch I posted a few minutes ago.  However, it DOES have something to do
with configuring with --disable-multibyte, because when I reconfigure
with --enable-multibyte all the tests run and pass.