Remove inet_ntoa() prototype from getrpcent.c

It is not needed.

In general, we shouldn't be using inet_ntoa(), anyway, as it is
IPv4-specific and we have IPv6 support almost everywhere.

src/lib/rpc/getrpcent.c

@@ -60,7 +60,6 @@ static struct rpcdata *get_rpcdata();
 
 static	struct rpcent *interpret();
 struct	hostent *gethostent();
-char	*inet_ntoa();
 
 static char RPCDB[] = "/etc/rpc";