octave delimited stream peek function

[Rik]

jwe,

I just fixed https://savannah.gnu.org/bugs/?56917, but it was incredibly
painful to find the root cause.  It turns out that the peek function for a
delimited_stream in oct-stream.cc does NOT necessarily return or set the
EOF indication when at the end of the file.  This is contrary to the C++
input stream behavior which returns what the next get() operation would
return (which in this case would be EOF).  I put a FIXME note in
oct-stream.cc, but is this a behavior that we are actually relying on and
want to keep?  I can't say for sure because I know there was a lot of
buffer optimization to support textscan() functionality.

--Rik