library/panic_unwind: Consolidate RV32 and RV64
library/panic_unwind: Consolidate RV32 and RV64

Signed-off-by: Alistair Francis <52ecf00b70a50079ae8d5fa09b9af6904950b63c@wdc.com>

aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust