The toolchain for this target is unmaintained since many years.

While it has been continuously build tested on fate, it hasn't
actually been tested at runtime since many, many years (and back
then, only a few codecs in libavcodec were tested).

So far, keeping support for it has been mostly effortless, but
the compiler does seem to have issues with dllimported data symbols,
ending up as internal compiler errors in some cases. Instead of
jumping through further hoops to work around that, just remove the
target.
Signed-off-by: Martin Storsjö <martin@martin.st>