IDN tests failing on Windows / MSYS2

[MarcelRaad]

I did this

See for example Marc's 6DY-SHZ-5KMWP2---- autobuilds, like this one:
https://curl.haxx.se/dev/log.cgi?id=20190407081751-30470

Note this:

=== Start of file stderr165
curl: (3) Failed to convert www.[EF][BF][BD][EF][BF][BD][EF][BF][BD].se to ACE;
curl: (3) Failed to convert www.gro[EF][BF][BD]e.de to ACE;
=== End of file stderr165

which doesn't happen when run in gdb, which is a native MSYS program, via ./runtests.pl -g (and the original URLs are printed correctly then).
So it seems like MSYS2 does some UTF-8-to-something-else conversion for Windows compatibility.

I expected the following

The tests to either succeed or not be executed (but preferably succeed as the MSYS2 terminal itself is UTF-8 capable).

curl/libcurl version

post-7.64.1 master 2f44e94

operating system

MSYS2 with MinGW-w64 on Windows 10

[MarcelRaad]

The problem is that curl receives its command-line arguments with ANSI encoding even though the perl precheck reports a UTF-8 locale. Using Windows's native UTF-16 for them as done in #3784 fixes this issue.

Only test 165 is then still failing because of ß handling in IDNA 2003 vs. 2008.