tsan: deflake test


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@204340 91177308-0d34-0410-b5e6-96231b3b80d8
[libsanitizer] Implement IntrusiveList<T>::Iterator, use IntrusiveList in sanitizer_flags.cc


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@204342 91177308-0d34-0410-b5e6-96231b3b80d8