devel/mingw32-gcc build difficulties

[Naram Qashat]

I've been trying to put together an update to devel/mingw32-gcc to bring it to 
gcc 4.8.1 (the current version that the official MinGW gcc is at). I'm not sure 
if poudriere is part of my issues or not, but here goes.

When building under a 9.x jail, the port pollutes PREFIX with 
/usr/local/mingw32/lib/COPIED and /usr/local/mingw32/sys-include/. I've no idea 
why they are left behind with 9.x (and I believe also 8.x as a previous redports 
build by rene@ seen here: 
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=191291#c2 shows) when they 
aren't left behind on 10.x or 11.x, but at the very least, these can be deleted 
in a post-build target without issues.

When building under a 10.x jail, though, the mingw32-gcc port seems to be 
clobbering some of the .a files that were installed by the 
devel/mingw32-bin-msvcrt port. At first, I thought it might've been because I 
had built a 10.x jail that was slightly newer than the world, but after 
rebuilding my 10.x jail to be 10.0-RELEASE (and thus no longer newer than my 
world), it still happens. I'm unable to get the build to finish under 10.x 
because /usr/local/mingw32/lib/libuser32.a from mingw32-bin-msvcrt contains 
nothing but nulls at the point where it tries to build libgcc_s_dw2-1.dll. 
Searching through the build log shows nothing pertaining to this other than it 
trying to link to the archive with -luser32. The archive isn't broken in 
mingw32-bin-msvcrt itself since I can install that and go into the jail and see 
that it has proper contents.

All in all, I would really like to push out an update to the port, but the 10.x 
difficulty is a stopping point currently.

Thanks in advance,
Naram Qashat