[LTO] Support filtering by hotness threshold

This wires up -pass-remarks-hotness-threshold to LTO and ThinLTO.

Next is to change the clang driver to pass this
with -fdiagnostics-hotness-threshold.

Differential Revision: https://reviews.llvm.org/D41465

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326107 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed