title: FindGit not working on iOS cross-compile
body: <p>We have a macOS where <code>git</code> is installed as part of XCode. It resides in <code>usr/bin</code>.</p>
  
  <p>Now when we use <code>find_package(Git REQUIRED)</code> it does not find <code>git</code>.</p>
  
  <ul>
  <li><code>which git</code> gives <code>/usr/bin/git</code></li>
  <li>Using the <code>find_program</code> call in <code>FindGit.cmake</code> fails.</li>
  <li>When looking at <code>CMAKE_SYSTEM_PREFIX_PATH</code>, there is an entry for <code>/usr</code>.</li>
  <li>Tested CMake versions are 3.5 and 3.7.1</li>
  <li>It only fails for cross-compilation to iOS (via Toolchain file)</li>
  </ul>
  
  <p>Really have no idea anymore why this fails.</p>