title: Qt Creator on MacOS: pkg-config dependencies can't be found
body: <p>I already tried all the solutions <a href="https://stackoverflow.com/questions/16972066/using-pkg-config-with-qt-creator-qmake-on-mac-osx">here</a>, but I continue to get the following error when I issue the command "Run qmake" on my project from Qt Creator on Qt 5.6.1:</p>
  
  <blockquote>
    <p>Project ERROR: grpc++ development package not found</p>
  </blockquote>
  
  <p>... Yet, on the console, <code>qmake &amp;&amp; make clean &amp;&amp; make</code> successfully builds the project with no errors.</p>
  
  <p><code>which qmake</code> returns <code>/usr/local/bin/qmake</code> and <code>qmake --version</code> returns</p>
  
  <pre><code>QMake version 3.0
  Using Qt version 5.6.1 in /usr/local/Cellar/qt5/5.6.1-1/lib
  </code></pre>
  
  <p>Here is my environment:</p>
  
  <ul>
  <li>macOS Sierra</li>
  <li>Qt SDK 5.7 (to get the latest version of Qt Creator)</li>
  <li>Homebrew installed Qt 5.6.1 (I need 5.6.x specifically for ABI compatibility)</li>
  <li>Dependencies <code>grpc++</code>, <code>libsndfile</code>, <code>protobuf</code> all installed via Homebrew in <code>/usr/local</code> and the <code>.pc</code> files are in /usr/local/lib/pkgconfig</li>
  </ul>
  
  <p>When I open up a new terminal and type <code>pkg-config --cflags --libs grpc++</code>, I get the correct result back with no error message.</p>
  
  <p>I'm trying to build this software, of which I am the primary author/maintainer: <a href="https://github.com/allquixotic/kynnaugh-cc" rel="nofollow noreferrer">https://github.com/allquixotic/kynnaugh-cc</a></p>
  
  <p>See the .pro file for details of how I'm telling it to use pkg-config.</p>
  
  <ul>
  <li>I've tried the <code>launchd.conf</code> hack from <a href="https://stackoverflow.com/questions/16972066/using-pkg-config-with-qt-creator-qmake-on-mac-osx">here</a> (and rebooted the Mac after updating it).</li>
  <li>I've tried the <code>/etc/paths.d/local</code> hack from the same question, to no avail.</li>
  <li>My .pro file has <code>QT_CONFIG -= no-pkg-config</code>.</li>
  <li>I tried setting the env var PKG_CONFIG_PATH=/usr/local/lib/pkgconfig explicitly in the "Manage Kits" GUI of Qt Creator for the Qt 5.6.1 toolchain that I'm using, but it didn't change the errant behaviour.</li>
  </ul>
  
  <p>Are there any other ways I can attempt to <em>diagnose</em> the problem, or can you spot an error in my .pro file, or is there a better solution to this problem than what I've attempted thus far?</p>
  
  <p>I'm asking this as a new question because <em>the solutions in <a href="https://stackoverflow.com/questions/16972066/using-pkg-config-with-qt-creator-qmake-on-mac-osx">that other question</a> don't work</em>, so I may very well be having a completely different problem despite extremely similar symptoms.</p>