Expand RISCV pseudo-instructions to match LLVM 11
Expand RISCV pseudo-instructions to match LLVM 11

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