[Debugify] Skip debugifying on special/immutable passes

[Debugify] Skip debugifying on special/immutable passes

With a function pass manager, it would insert debuginfo metadata before
getting to function passes while processing the pass manager, causing
debugify to skip while running the function passes.

Skip special passes + verifier + printing passes. Compared to the legacy
implementation of -debugify-each, this additionally skips verifier
passes. Probably no need to update the legacy version since it will be
obsolete soon.

This fixes 2 instcombine tests using -debugify-each under NPM.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D91558