tsan: disable __tls_get_addr interceptor

see the added comments for details, it's messy



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@224531 91177308-0d34-0410-b5e6-96231b3b80d8
tsan: add an additional test for signal handlers

the test passes now, but signal handling during thread creation
and shutdown is tricky



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@224532 91177308-0d34-0410-b5e6-96231b3b80d8