Radius: remove anonymous namespace, it doesn't compile with it

src/lib/dhcpsrv/radius_host_data_source.cc

@@ -33,8 +33,6 @@ using namespace isc::dhcp;
 using namespace isc::util;
 using namespace std;
 
-namespace {
-
 /// @brief Maximum size of an IPv6 address represented as a text string.
 ///
 /// This is 32 hexadecimal characters written in 8 groups of four, plus seven