getdata: split busy function to segments used via function pointer

When it is known IPv4 is in use there is no need to spend time with if
statements checking whether IPv6 is in use.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

src/dhcpd-pools.c

@@ -248,6 +248,7 @@ int main(int argc, char **argv)
 
 	/* Do the job */
 	prepare_memory();
+	xstrstr = xstrstr_init;
 	parse_config(true, config.dhcpdconf_file, shared_networks);
 
 	parse_leases();