when TSystem::GetHostByName() returns "UnNamedHost" set the host name

in TInetAddress by the address in dot notation. This avoids all kind of
ugly tests on "UnNamedHost" in user code, and more importantly this test
was not always done resulting in failed connections to a host "UnNamedHost"
which does not exist.


git-svn-id: http://root.cern.ch/svn/root/trunk@24777 27541ba8-7e3a-0410-8455-c3a389f83636