cdr_radius, cel_radius: build agains libfreeradius-client

Asterisk's RADIUS module currently build against libradiusclient-ng, but this
project has been superseeded by libfreeradius-client. The API is 99% compatible
except that the header name has changed, the library name has changed, and
the configuration file location has changed.

(closes issue ASTERISK-22980)
Reported by: Jeremy Lainé
Patches:
     freeradius-client.patch uploaded by sharky (license 6561)
........

Merged revisions 406801 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/11@406802 f38db490-d61c-443f-a65b-d21fe96a405b