Since connman is specific to linux, on other platforms just compile a
dummy "none" backend that will always report online and no other
details. This will be used in Windows, MacOS and other platforms that
still lack a proper backend.
The compile-time infrastructure also allows for networkmanager to be
added with ease, simply copy "efl_net*-none.c" or "efl_net*-connman.c"
to be a starting point and then add its specifics, adapting
configure.ac and Makefile_Ecore_Con.am