tcg/riscv: Improve setcond expansion

tcg/riscv: Improve setcond expansion

Split out a helper function, tcg_out_setcond_int, which does not
always produce the complete boolean result, but returns a set of
flags to do so.

Based on 21af16198425, the same improvement for loongarch64.

Acked-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>