tcg/tci: Implement mulu2, muls2

We already had mulu2_i32 for a 32-bit host; expand this to 64-bit
hosts as well.  The muls2_i32 and the 64-bit opcodes are new.

Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>