new package: freeradius-client

Signed-off-by: David Bender <codehero@gmail.com>
[yann.morin.1998@free.fr:
  - add optional dependency to nettle
  - fix build against nettle
  - switch to using the ftp for release, instead of github
  - add missing dependency to host-pkgconf
  - remove extraneous configure options, we already pass them
  - drop extraneous ac_cv_func_memcmp_working, we already pass it
  - drop extraneous ac_cv_func_uname, it is properly found
  - add hash file
  - tweak help entry
]
[Peter: license is BSD-2c]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>