Terminates the GLFW library.
This function destroys all remaining windows and cursors, restores any
modified gamma ramps and frees any other allocated resources. Once this
function is called, you must again call
you will be able to use most GLFW functions.
If GLFW has been successfully initialized, this function should be called
before the application exits. If initialization fails, there is no need to
call this function, as it is called by
before it returns
This function has no effect if GLFW is not initialized.