title: Freetype headers cant be found even though freetype is included with cmake
body: <p>I'm trying to include FreeType with cmake but am having issues with ft2build.h not being found. Here are my cmake files</p>
  <p>main cmakelist:</p>
  <pre><code>cmake_minimum_required(VERSION 2.8)
  
  project(game)
  
  add_subdirectory(Managers)
  add_subdirectory(Core)
  add_subdirectory(Rendering)
  add_subdirectory(Input)
  
  add_executable(game main.cpp)
  
  target_link_libraries(game initglew initglut camera modelmanager scenemanager shadermanager renderinglib)
  
  find_library(GLUT glut)
  find_library(OPENGL GL)
  find_library(GLEW GLEW)
  find_library(MATH m)
  
  find_package(Freetype REQUIRED)
  
  target_link_libraries(game ${GLUT} ${OPENGL} ${GLEW} ${MATH} ${FREETYPE_LIBRARIES})
  include_directories(${FREETYPE_INCLUDE_DIRS})
  
  SET(GCC_FLAGS &quot;-Wall -Wextra -pedantic -std=c++17 -Wno-unused-parameter -g&quot;)
  add_definitions(${GCC_FLAGS})
  
  install(TARGETS game DESTINATION bin)
  </code></pre>
  <p>Rendering cmakelist:</p>
  <pre><code>cmake_minimum_required(VERSION 2.8)
  
  project(rendering)
  file(GLOB_RECURSE renderingcpps CONFIGURE_DEPENDS &quot;*.cpp&quot;)
  file(GLOB_RECURSE renderinghpps CONFIGURE_DEPENDS &quot;*.hpp&quot;)
  
  add_library(renderinglib STATIC ${renderingcpps})
  
  install(TARGETS renderinglib DESTINATION lib)
  
  install(FILES ${renderinghpps} DESTINATION include)
  
  </code></pre>
  <p>I'm including FreeType in the highest level cmakelist but a file inside a subfolder of rendering cant find ft2build.h. I tried following this link
  <a href="https://stackoverflow.com/questions/23888274/linking-freetype-with-cmake">Linking freetype with cmake</a>
  which got me where I am now but ft2build.h still cant be found. I was originally compiling with &quot;-lfreetype -I/usr/include/freetype2&quot; before trying to switch to cmake</p>
  <p>I logged some output and FREETYPE_INCLUDE_DIRS is being populated with /usr/include/freetype2 but its two subcomponets are empty, not sure if thats related</p>