Windows: Avoid an error message on broken pipe

Windows: Avoid an error message on broken pipe

Also make xz not process more input files after a broken pipe has
been detected. This matches the behavior on POSIX. If all files
are being written to standard output, trying with the next file is
pointless when it's known that standard output won't accept more data.

xzdec already stopped after the first error. It does so with all
errors, so it differs from xz:

    $ xz -dc not_found_1 not_found_2
    xz: not_found_1: No such file or directory
    xz: not_found_2: No such file or directory

    $ xzdec not_found_1 not_found_2
    xzdec: not_found_1: No such file or directory

Reported-by: Vincent Torri