title: QtCreator and pkg-config
body: <p>I imported a makefile project into Qt creator for more productive development. When I use make in the terminal:</p>
  
  <pre><code>g++  Size3.o SteerableTests.o MyLib.o Tensor.o Cube.o Steerable.o -lUnitTest++ `pkg-config --libs opencv` -o steerable
  </code></pre>
  
  <p>It compiles successfully. But when using build option of QtCreator, it keeps saying that pkg-config can't find opencv. How to set the environment path for QtCreator?</p>
  
  <pre><code>11:35:21: Starting: "/usr/bin/make" all
  g++  Size3.o SteerableTests.o MyLib.o Tensor.o Cube.o Steerable.o -lUnitTest++ `pkg-config --libs opencv` -o steerable
  Package opencv was not found in the pkg-config search path.
  Perhaps you should add the directory containing `opencv.pc'
  to the PKG_CONFIG_PATH environment variable
  No package 'opencv' found
  </code></pre>