- Retainer profiler: init_srt_thunk() should mark the stack entry as SRT
- Retainer profiler: Remove an incorrect assertion about FUN_STATIC.
  FUN_STATIC does not have to have an SRT.
- Fix nptrs of BCO

Test Plan: validate

Reviewers: simonmar, bgamari, erikd

Reviewed By: simonmar

Subscribers: rwbarton, carter

Differential Revision: https://phabricator.haskell.org/D5134