Convert multiplies to running adds

If a proc has a state element `x` that is continually incremented (`x_next = x + delta_x`), and somewhere in the proc body `y = k * x` is computed, the code can be modified to replace the multiply by a register and an add (`y_next = y + (k * delta_x)`). This will require some basic notion of scalar evolution to determine that `x` is continually incremented.