Revert "Restore "[MemProf] ThinLTO summary support" with fixes"

This reverts commit 00c22351.
This reverts commit 98ed4233.

Seemingly MSVC has some kind of issue with this patch, in terms of linking:

  https://lab.llvm.org/buildbot/#/builders/123/builds/14137

I'll post more detail on D135714 momentarily.