x86: swap operands in OUT-with-immediate template

x86: swap operands in OUT-with-immediate template

In a number of places we assume that immediates come first in the set of
operands. It is mere luck that so far OUT, having operands the other way
around, wasn't negatively impacted by this.

Leverage this to have a few loops start from the first non-immediate
operand (or in one case to stop there). Note, however, that
process_immext() inserts an immediate last, so especially all output_*()
functions cannot be changed in the same way.