patch 9.1.2099: different line endings in ja.sjis.po and ja.po

patch 9.1.2099: different line endings in ja.sjis.po and ja.po

Problem:  Depending on the worker's environment, the line endings in
          ja.sjis.po may differ from those in the source ja.po.

Solution: By setting standard input and output to binary mode, the line
          endings for input and output will match (Muraoka Taro)

This occurs when using MINGW gcc on Windows and git with autocrlf=false.
In this case, the line endings in ja.po are LF, but because sjiscorr
compiled with MINGW gcc uses text mode for standard input and output,
the line endings in the output ja.sjis.po will be CRLF.

This mismatch in line endings confuses git, causing large differences to
occur when updating.

In addition, the comment style has been changed to // to match the rest
of Vim's code.

closes: #19226

Signed-off-by: Muraoka Taro <koron.kaoriya@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>