Summary:
We were erroneously discarding SCCs on function-typed variables.
These can affect the call stack, so we have to retain them.  The bug
was introduced during the recent SourceNote refactoring.

This is an alternative to the fix proposed in D616.  I also added the
scc005 test from that diff, which works with this change.

While I was here, I also fixed up the other profiling tests, marking a
few as expect_broken_for(10037) where the opt/unopt output differs in
non-fatal ways.

Test Plan: profiling tests

Reviewers: scpmw, ezyang, austin

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D636

GHC Trac Issues: #10007