Andy,

I took a stab at porting RISC-V from lightning to lightening.
I have no riscv toolset or computer yet so these are untested.

I copied files from sv/lightning for riscv to wingo/lightening. Patch 
attached.
The changes are:
1) copy lightning/jit_riscv{.c,-cpu.c-fpu.c,-sz.c,.h} to lightening
2) s/include "jit_riscv/include "riscv/
3) s/git_int/int/ and s/git_uint/uint/
4) copied the JIT_RA0, etc defines from jit_private.h to riscv.c
5) updated lightening.am
6) updated lightening.h

Matt