tsan: allow to override OnFinalize() in front-ends that does not support weak functions (Go)



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@192569 91177308-0d34-0410-b5e6-96231b3b80d8
[Sanitizer] Return implementation of StackTrace::CopyFrom to header

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@192574 91177308-0d34-0410-b5e6-96231b3b80d8