title: switching from Qt 5.6 to Qt 5.7 - "no member 'make_unique' in namespace std"
body: <p>I have a CMake Qt project which uses several c++14 features, including <code>std::make_unique</code>. Typically this would be handled either by:</p>
  
  <pre><code>LIST(APPEND CMAKE_CXX_FLAGS -std=c++14)
  </code></pre>
  
  <p>or</p>
  
  <pre><code>ADD_COMPILE_OPTIONS(-std=c++14)
  </code></pre>
  
  <p>I'd like to upgrade the project from version 5.6 to 5.7, but during a test build there were multiple failures with the error </p>
  
  <blockquote>
    <p>no member 'make_unique' in namespace std</p>
  </blockquote>
  
  <p>I've verified all the appropriate headers and compile options are in place, and ruled out any environment problems. It's definitely an issue with using Qt 5.7. Is there any workaround?</p>