title: CMAKE_PREFIX_PATH doesn't help CMake in finding Qt5
body: <p>From here: <a href="https://stackoverflow.com/a/28327499/462608">https://stackoverflow.com/a/28327499/462608</a></p>
  
  <p><strong>I tried this:</strong></p>
  
  <pre><code>cmake_minimum_required(VERSION 2.8.12)
  
  project(qtquick_hello_cmake)
  
  set(CMAKE_PREFIX_PATH "/opt/Qt5.9.1/5.9.1/")
  
  set(CMAKE_INCLUDE_CURRENT_DIR ON)
  set(CMAKE_AUTOMOC ON)
  set(CMAKE_AUTORCC ON)
  
  find_package(Qt5 COMPONENTS Quick Core REQUIRED)
  
  qt5_add_resources(RESOURCES qml.qrc)
  
  add_executable(${PROJECT_NAME} "main.cpp" "qml.qrc")
  
  qt5_use_modules(${PROJECT_NAME} Quick Core)
  
  target_link_libraries(${PROJECT_NAME} Qt5::Core Qt5::Quick)
  </code></pre>
  
  <p><strong>Here is the output of <code>cmake .</code></strong></p>
  
  <pre><code>:~/junk/qtquick_hello_cmake$ cmake .
  CMake Error at CMakeLists.txt:11 (find_package):
    By not providing "FindQt5.cmake" in CMAKE_MODULE_PATH this project has
    asked CMake to find a package configuration file provided by "Qt5", but
    CMake did not find one.
  
    Could not find a package configuration file provided by "Qt5" with any of
    the following names:
  
      Qt5Config.cmake
      qt5-config.cmake
  
    Add the installation prefix of "Qt5" to CMAKE_PREFIX_PATH or set "Qt5_DIR"
    to a directory containing one of the above files.  If "Qt5" provides a
    separate development package or SDK, be sure it has been installed.
  
  
  -- Configuring incomplete, errors occurred!
  See also "/home/.../junk/qtquick_hello_cmake/CMakeFiles/CMakeOutput.log".
  </code></pre>
  
  <p><strong>This is to show that <code>/opt/Qt5.9.1/</code> does exist.</strong></p>
  
  <pre><code>:~/junk/qtquick_hello_cmake$ cd /opt/Qt5.9.1/5.9.1/
  :/opt/Qt5.9.1/5.9.1$ ls
  android_armv7  android_x86  gcc_64  Src
  </code></pre>
  
  <p><strong>Here I run the cmake with -DCMAKE option, but the output is still same:</strong></p>
  
  <pre><code>:~/junk/qtquick_hello_cmake$ cmake -DCMAKE_PREFIX_PATH=/opt/Qt5.9.1/5.9.1/ -DWITH_QT5=1 .
  CMake Error at CMakeLists.txt:11 (find_package):
    By not providing "FindQt5.cmake" in CMAKE_MODULE_PATH this project has
    asked CMake to find a package configuration file provided by "Qt5", but
    CMake did not find one.
  
    Could not find a package configuration file provided by "Qt5" with any of
    the following names:
  
      Qt5Config.cmake
      qt5-config.cmake
  
    Add the installation prefix of "Qt5" to CMAKE_PREFIX_PATH or set "Qt5_DIR"
    to a directory containing one of the above files.  If "Qt5" provides a
    separate development package or SDK, be sure it has been installed.
  
  
  -- Configuring incomplete, errors occurred!
  See also "/home/.../junk/qtquick_hello_cmake/CMakeFiles/CMakeOutput.log".
  </code></pre>
  
  <p><strong>Contents of the directory:</strong></p>
  
  <pre><code>:~/junk/qtquick_hello_cmake$ ls
  CMakeCache.txt  CMakeFiles  CMakeLists.txt  main.cpp  main.qml  qml.qrc
  </code></pre>