tsan: expose atomic operations in Go runtime



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@213382 91177308-0d34-0410-b5e6-96231b3b80d8
tsan: fix Go runtime build with clang



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@213384 91177308-0d34-0410-b5e6-96231b3b80d8