--enable-mingw32 hasn't ever worked for me.  The follow patch is a set 
of changes to configure so that --cross-prefix=i586-mingw32-msvc does 
the right thing.

It needs some testing.  It works for me but I don't know if people have 
weird setups where the gcc cross prefix != the sdl cross prefix or 
something odd like that.

Regards,

Anthony Liguori