Fix mingw detection in ucrt64 environment

[calebkiage]

#3960

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[calebkiage]

Should is_host("windows") be replaced with is_host("windows") and not is_subhost("msys", "cygwin") in lua?

[waruqi]

Should is_host("windows") be replaced with is_host("windows") and not is_subhost("msys", "cygwin") in lua?

no, msys/cygwin is also on windows

[calebkiage]

Yes, but the msys shell behaves like linux.
For example:

    if is_host("windows") and not opt.rawargs then
        argv = winos.cmdargv(argv, {escape = true})
    end

msys shell shouldn't have a character limit

[waruqi]

Yes, but the msys shell behaves like linux. For example:

    if is_host("windows") and not opt.rawargs then
        argv = winos.cmdargv(argv, {escape = true})
    end

msys shell shouldn't have a character limit

this limit is from CreateProcess, not shell. msys2 has also this problem.

[calebkiage]

What about /dev/null handling?

[waruqi]

please use os.nuldev()