Remove the lower_br_fcmp function from the riscv64 backend. This PR only affects the emit implementation for FloatRound, replacing the uses of lower_br_fcmp with direct uses of FpuRRR and CondBr. Any changes in behavior here should be already covered by the runtests for ceil, floor, trunc, and nearest.
This crate contains the core Cranelift code generator. It translates code from an intermediate representation into executable machine code.