Fixes for MSVC compilation

[John W. Eaton]

On 12-Nov-2008, Michael Goffioul wrote:

| I finally managed to get current octave archive compiled with MSVC.
| The changeset is attached. OK to commit?

Yes, I think it would be OK.

Is it necessary to indent the

  # undef min

line?  I don't object to this style, but if we are going to use it,
maybe we should use it consistently in the rest of the Octave sources.

jwe