and use that to fix up usused variable declarations and parameters that
are caused by transformations.
also add a transformation to replace global variable init with
`undefined`.
Now it works like this:
1. Walk the AST of the source file looking for independent
reductions and collecting them all into an array list.
2. Randomize the list of transformations. A future enhancement will add
priority weights to the sorting but for now they are completely
shuffled.
3. Apply a subset consisting of 1/2 of the transformations and check for
interestingness.
4. If not interesting, half the subset size again and check again.
5. Repeat until the subset size is 1, then march the transformation
index forward by 1 with each non-interesting attempt.
At any point if a subset of transformations succeeds in producing an interesting
result, restart the whole process, reparsing the AST and re-generating the list
of all possible transformations and shuffling it again.
As for std.zig.render, the fixups operate based on AST Node Index rather
than Nth index of the function occurence. This allows precise control
over how to mutate the input.
