RISC V support.

[necrose99]

riscv-0.4.0.ebuild.txt

https://wiki.gentoo.org/wiki/User:Maffblaster/Projects/RISC-V

https://github.com/riscv/riscv-gentoo-infra

https://riscv.org/

While I could pull this its i quickly made with cargo ebuild as a test of windows rust update ...
thankfully I have Windows/sabayon(Gentoo) on SSD's. time permitting , I may do so.. unfortunately till cable/ FIOS is added to my new complex , internet availability is spotty at best.

@Maffblaster or other Gentoo Infra-devs doing RISC-V Single board pc ports , might have use of this
as RISC V SBC's a bit expensive for now... despite bing completely opensource CPU and GPU extensions.