Patch #156545 is introducing a different syntax for the 'destroy'
section of a recipe, which takes the 'original' value as the first
argument, and the one-to-be-destroyed as the 2nd. This patch corrects
the lowering to match that signature.

As a follow on to the last patches of this form, this patch does the
init section for all of the reduction operators that weren't previously
covered, which is '&' as all-ones, 'max' as 'least', and 'min' as
'largest'.

The * and && operators of a reduction require a starting value of '1'.
This patch implements that by looping through every type and creating an
init-list that puts a 1 in place of every initializer.

This patch will be followed up by a patch that generalizes this, as
`min`, `max`, and `&` all have different initial values.

These four operators have an initial value of 0, so they are able to use
C/C++ 'zero init'. This patch adds the infrastructure to the Sema init
calculations to differentiate based on the reduction operator, then
enables emission of the inits in CodeGen (which should work for all
    inits, once generated).

The rest of this test is just updating validation to make sure that the
inits happen correctly for all 4 operators.

This patch implements basic reduction recipe lowering, plus adds a bunch
of tests for it that should be meaningful later. At the moment, all this
does is ensure that we get the init 'alloca' set right (the actual
initializer isn't done correctly yet, and will be in a followup), an
empty combiner (though the type of certain operations probably has to be
different as well, when we get to those), and a full-destruction, as we
already have the infrastructure for it.