Fix linking error on ubuntu

[dcanelhas]

using the cmake variable for glfw fixes the following linking error:

Linking CXX executable ../bin/alienrain
/usr/bin/ld: cannot find -lglfw3
collect2: error: ld returned 1 exit status
make[2]: *** [../bin/alienrain] Error 1
make[1]: *** [CMakeFiles/alienrain.dir/all] Error 2
make: *** [all] Error 2

[mxncr]

Also fix the issue on Arch, thanks

[bclinthall]

This worked for me on Ubuntu. I couldn't compile without it.

[RemusRomulus]

Will try this for CentOS7

[bdaase]

Why is this not merged?

[OdairTrujillo]

Aditional to edit the line 28 with the GLFW_LIBRARIES variable inside the CMakeLists.txt file:

set(COMMON_LIBS sb7 ${GLFW_LIBRARIES} X11 Xrandr Xinerama Xi Xxf86vm Xcursor GL rt dl)

Also I had to install the following dependencies in Ubuntu 20.04:

libxi-dev
libxcursor-dev
libxinerama-dev
libxxf86vm-dev

And I had to run cmake like this:
cmake .. -DOpenGL_GL_PREFERENCE=GLVND

In order to ensure the use of the NEW policy for CMP0072 policy.