Add !callees metadata

This patch adds a new kind of metadata that indicates the possible callees of
indirect calls.

Differential Revision: https://reviews.llvm.org/D37354

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315944 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed