Problem Compiling

Hello guys.

I become interested in this project and I'd like to understand the code and help in what I can.

I checkout the project and installed everything needed.

I'm using Arch Linux.

So when I try to compile it says 

CMake Error at /usr/lib/cmake/Qt5Gui/Qt5GuiConfigExtras.cmake:9 (message):
  Failed to find "GL/gl.h" in "/usr/include/libdrm".
Call Stack (most recent call first):
  /usr/lib/cmake/Qt5Gui/Qt5GuiConfig.cmake:184 (include)
  /usr/lib/cmake/Qt5Widgets/Qt5WidgetsConfig.cmake:101 (find_package)
  /usr/lib/cmake/Qt5/Qt5Config.cmake:28 (find_package)
  CMakeLists.txt:9 (find_package)

If I go to /usr/inclued/GL there is the gl.h. 

Where can I change the script to detect the gl library ? Never worked before with CMake.

Thanks for your attention.
Best regards!