title: What is the current state of support for 'thread_local' across platforms?
body: <p>I'd like a summary of what the current state of support for the 'thread_local' keyword is across different compilers and platforms. </p>
  
  <p>I'm specifically interested in common desktop and mobile platforms. The information I could find seems spotty at best with reports of it working on some platforms and not on others or mentions of support being a WIP. Answers that confirm support (or lack of support) even for single platforms are welcome. Please mention any caveats to the support if there are any.</p>
  
  <ul>
  <li>Windows (gcc, clang, msvc)</li>
  <li>Linux (gcc, clang)</li>
  <li>OS X (gcc, clang)</li>
  <li>Android (gcc, clang)</li>
  <li>iOS</li>
  <li>BlackBerry</li>
  <li>Windows Phone/RT/etc</li>
  </ul>