[RFA] fix mingw32 --enable-targets=all --enable-64-bit-bfd failure in or1k-desc.h

[Frank Ch. Eigler]

Hi, Alan -

> [...]  Which reminds me.  Frank, is there any chance of
> https://sourceware.org/ml/cgen/2014-q2/msg00001.html being committed
> so I can turn back on --enable-cgen-maint for binutils builds?

Please feel free to go ahead (this is a port-maintainer-level issue).

- FChE