[clang] [clang][docs] Document ThreadSanitizer run-time flags and suppressions (PR #205761)

[Alexander Potapenko via cfe-commits]

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@@ -187,6 +198,24 @@ Limitations
   ``fsanitize=thread`` flag will cause Clang to act as though the ``-fPIE``
   flag had been supplied if compiling without ``-fPIC``, and as though the
   ``-pie`` flag had been supplied if linking an executable.
+* ThreadSanitizer does not support C++ exceptions. Programs relying heavily on
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ramosian-glider wrote:

Dmitry agreed offline that dropping this part is reasonable.

https://github.com/llvm/llvm-project/pull/205761