I can't help you with that, but I wanted to point out that I've
successfully built svn head on MinGW just a few hours ago
trying to build the latest llvm-gcc-4.2 is on the contrary proving
much much more problematic, as I observe a strange error ("xgcc.exe:
Invalid Argument") using either mingw-gcc-3.4.5 or 4.2.1(in the latter
case both with dw2 and sjlj, even tough that's probably irrelevant)
of course if there's anyone around who managed to do that, I'd like to
see your recipe.