[Polly] Make the NewPM pass pipeline more similar to the legacy's.

Even though it has some oddities, both pipelines should be as similar as
possible. Also use report_fatal_error instead of assertions to ensure a
proper failure in release builds for unsupported options.

This finalizes the patch serious to make Polly run in the default
configuration when using the NewPM by default.

GitOrigin-RevId: 222d380d2f57cc71bb613b5c01ecf17cd1f61fa2
1 file changed