[Bug 40460] winetricks xna31 and dotnet20sp2 fail

https://bugs.winehq.org/show_bug.cgi?id=40460

--- Comment #8 from Sebastian Lackner  ---
(In reply to Austin English from comment #7)
> That wasn't enough for me, I also tried it after both w_call dotnet20 and
> the dotnet20sp2 installer, but that only works sometimes.

Hm, here it works pretty reliable. I'll see if I can reproduce the issue when I
run the testcase in a loop. ;)
> > BTW: At some places winetricks uses $DRIVE_C which looks like an undefined
> > variable to me.
>
> It's set in winetricks_set_wineprefix(), which is called from w_do_call().

I only see W_DRIVE_C there, but not DRIVE_C (unless some weird eval magic is
involved to set it).