Constant operands of commutative operations preferably go on the right
hand side to avoid requiring an extra register for two operand
instructions. Also, Subzero assumes constants in pointer arithmetic are
on the right hand side to consider optimizing it into an addressing
mode.

Change-Id: Ife5a471903d5f4bef0c19b6c908d75715f06bfec
Reviewed-on: https://swiftshader-review.googlesource.com/8548Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>