disable HAVE_THREAD_LOCAL on unreliable platforms
disable HAVE_THREAD_LOCAL on unreliable platforms

Note that this doesn't affect anything unless
DEBUG_LOCKCONTENTION is defined.

See discussions here:

- https://github.com/bitcoin/bitcoin/pull/11722#pullrequestreview-79322658
- https://github.com/bitcoin/bitcoin/pull/13168#issuecomment-387181155

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