Implement trampoline and handler for typed xray event tracing.

Summary:
Compiler-rt support first before defining the __xray_typedevent() lowering in
llvm. I'm looking for some early feedback before I touch much more code.

Reviewers: dberris

Subscribers: delcypher, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D43668

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@330218 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed