[asan] Workaround to avoid hangs in Chromium tests

[asan] Workaround to avoid hangs in Chromium tests

Summary:
For some reasons on Chromium when we start leak checking we get own pid as 1.
After that we see threads with PPID:0 assuming that thread is dead in infinite
loop.

To resolve particularly this case and possible issues like this, when IsAlive check failed to detect thread status, we need to limit the number of SuspendAllThreads
iterations.

Reviewers: eugenis

Subscribers: kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D46852

llvm-svn: 332319