Win32: resolve some symbols re-definition of windows.h in glfw3native.h (#2643)
* Win32: resolve some symbols re-definition of windows.h in glfw3native.h
This reflects GLFW's fix: https://github.com/glfw/glfw/issues/1348
This enables to build with a external GLFW containing the
following fix:
* 05f6c13d11
Currently, glfw3native.h of the internal GLFW is customized at
2feea87b61
This fix is compatible with the current customized glfw3native.h.
This fix enables us to update it to the latest and remove the
customization.
* Win32: remove unneeded typedef