using a slightly older version of devel/mingw32-gcc

  mingw32-gcc-4.7.2_1,1

I attempted to build it using the unmodified port, but had a problem with a specific include file "unwind.h".  it appears that if another port/package (such as devel/libunwind) is installed, and places a duplicate-name header file into /usr/local/include, then the mingw32-gcc build may not work properly (#includes the wrong file, basically).

The solution appears to be to comment out (or remove) the following line in Makefile :

CFLAGS+=       -I${LOCALBASE}/include

Without this addition to CFLAGS, the configure script STILL includes /usr/local/include in its search path; however, it appears LATER in the command line and thereby this prevents problems with aliasing of include files from /usr/local/include.

On examination of the Makefile in 'freshports', it appears that the latest will have the same problem.  In effect, ANY installed port that produces an incompatible include file that aliases one needed by the gcc build will result in the SAME kinds of problems, maybe even causing crashes, etc.

Other gcc cross-compilers should be checked to see if they do the same thing. Header file aliasing could easily mess THEM up as well.