Fix SF #1599879, socket.gethostname should ref getfqdn directly.

Doc/lib/libsocket.tex

@@ -241,8 +241,8 @@ If you want to know the current machine's IP address, you may want to use
 This operation assumes that there is a valid address-to-host mapping for
 the host, and the assumption does not always hold.
 Note: \function{gethostname()} doesn't always return the fully qualified
-domain name; use \code{gethostbyaddr(gethostname())}
-(see below).
+domain name; use \code{getfqdn()}
+(see above).
 \end{funcdesc}
 
 \begin{funcdesc}{gethostbyaddr}{ip_address}