REORG: server: use flags for parse_server

Modify the API of parse_server function. Use flags to describe the type
of the parsed server instead of discrete arguments. These flags can be
used to specify if a server/default-server/server-template is parsed.
Additional parameters are also specified (parsing of the address
required, resolve of a name must be done immediately).

It is now unneeded to use strcmp on args[0] in parse_server. Also, the
calls to parse_server are more explicit thanks to the flags.
diff --git a/src/resolvers.c b/src/resolvers.c
index f356492..c14b970 100644
--- a/src/resolvers.c
+++ b/src/resolvers.c
@@ -2971,7 +2971,8 @@
 		HA_SPIN_INIT(&curr_resolvers->lock);
 	}
 	else if (strcmp(args[0],"server") == 0) {
-		err_code |= parse_server(file, linenum, args, curr_resolvers->px, NULL, 1, 0, 1);
+		err_code |= parse_server(file, linenum, args, curr_resolvers->px, NULL,
+		                         SRV_PARSE_PARSE_ADDR|SRV_PARSE_INITIAL_RESOLVE);
         }
 	else if (strcmp(args[0], "nameserver") == 0) { /* nameserver definition */
 		struct dns_nameserver *newnameserver = NULL;