Add a script that is used to deflake inherently flaky tsan tests.
It is invoked from lit tests as:
%deflake %run %t
The script runs the target program up to 10 times,
until it produces a tsan warning.
llvm-svn: 209898
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
llvm-svn: 206754