Fixing problems when including headers form an other project

If you include the headers form an other project. Then all the values of
config.h (especially HAVE_LITTLE_ENDIAN and HAVE_BIG_ENDIAN) are not
set. I now sperated the endian checks into `ntb-endian` and only include them
where it is nessassery.
Remove EPOLLRDHUP

EPOLLRDHUP is not available on Android.