.arcconfig

setup: build exewrapper with Unicode support on py3

I didn't see a compiler switch documented anywhere, but I diffed the command
line for full VC++ project when toggling between MBCS and Unicode.  This is all
they do.

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}