msys-gzip: add .bat wrappers to shellscripts * tools/gen-bat-wrapper: new file * dist-files.mk: add gen-bat-wrapper * src/msys-gzip.mk: add find of shell script and create .bat file

#!/usr/bin/env bash

prog=$1

if [ -z $prog ]; then
  echo "Missing program name" >&2
  exit 1
fi

cat << EOF
@echo off
set BINPATH=%~dp0
%BINPATH%bash -c '$prog %*'
EOF