On Fri, Sep 29, 2017 at 5:37 AM, Eli Zaretskii <eliz@gnu.org> wrote:

>> > Vincent Belaďche wrote:
>> >
>> >> There is no such thing as a mingw64_shell.bat script, but there is a
>> >> msys2_shell.cmd script, which one can launch with the -mingw64 for
>> >> MSYSTEM to be set accordingly to MSYSTEM=MINGW64.

> Can you or someone else suggest a change for INSTALL.W64, if some
> change is needed there?

The attached should do it.