problem building mingw cross compiler

[Jeremy Lavergne]

> I have now found the following ticket:
>     http://trac.macports.org/ticket/30349
>
> Changing the compiler with
>
> if {${configure.compiler} == "llvm-gcc-4.2"} {
>    configure.compiler gcc-4.2
> }
>
> indeed works fine and basic cross-compilation seems to work with the
> binary that I get.

Added that change in r85313.