Move EntryExitInstrumentation pass location

This seems to be more of a Clang thing rather than a generic LLVM thing,
so this moves it out of LLVM pipelines and as Clang extension hooks into
LLVM pipelines.

Move the post-inline EEInstrumentation out of the backend pipeline and
into a late pass, similar to other sanitizer passes. It doesn't fit
into the codegen pipeline.

Also fix up EntryExitInstrumentation not running at -O0 under the new
PM. PR49143

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D97608