Fixes mismatched location of GLFW includes on some Linux distributions

In Arch Linux, Fedora and some other distros GLFW resides at /usr/include. As quick fix searching both locations will work well. Similar fix was applied before in main cocos CMakeLists file.  A more fundamental solution making Cmake search for library by itself (one example https://code.google.com/p/assembly3d/source/browse/tools/viewer/cmake_scripts/FindGLFW.cmake) seems overkill.