[Bf-committers] build blender with mingw

[Antony Riakiotakis]

SDL, iconv and gettext are a go here. FFMpeg also produced errors so I
disabled (which is painful on cmake because you also have to disable
openexr/tiff/cycles...If it cycles/openexr/tiff work on scons with
ffmpeg off then it is definitely a link order issue on cmake that I
should figure out). For ffmpeg I want to consult Sergey because he is
the master there.