When building NVTT on raspbian and some other linuxes (I believe @Freagarach reported it too) I get the following warning
```
CMake Warning (dev) at /usr/share/cmake-3.13/Modules/FindOpenGL.cmake:270 (message):
Policy CMP0072 is not set: FindOpenGL prefers GLVND by default when
available. Run "cmake --help-policy CMP0072" for policy details. Use the
cmake_policy command to set the policy and suppress this warning.
FindOpenGL found both a legacy GL library:
OPENGL_gl_LIBRARY: /usr/lib/arm-linux-gnueabihf/libGL.so
and GLVND libraries for OpenGL and GLX:
OPENGL_opengl_LIBRARY: /usr/lib/arm-linux-gnueabihf/libOpenGL.so
OPENGL_glx_LIBRARY: /usr/lib/arm-linux-gnueabihf/libGLX.so
OpenGL_GL_PREFERENCE has not been set to "GLVND" or "LEGACY", so for
compatibility with CMake 3.10 and below the legacy GL library will be used.
Call Stack (most recent call first):
src/CMakeLists.txt:20 (INCLUDE)
This warning is for project developers. Use -Wno-dev to suppress it.
```