[asan] add a run-time flag detect_container_overflow=true/false

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@206753 91177308-0d34-0410-b5e6-96231b3b80d8
tsan: deflake test
ocasionally it fails with a slightly different report:

WARNING: ThreadSanitizer: signal handler spoils errno (pid=3674)
    #0 MyHandler(int, siginfo*, void*)
    ...
    #4 __tsan_free_hook
    #5 main signal_errno.cc:40



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@206754 91177308-0d34-0410-b5e6-96231b3b80d8
[sanitizer] Intercept tsearch.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@206755 91177308-0d34-0410-b5e6-96231b3b80d8