MINOR: receiver: reserve special values for "shards"

Instead of artificially setting the shards count to MAX_THREAD when
"by-thread" is used, let's reserve special values for symbolic names
so that we can add more in the future. For now we use value -1 for
"by-thread", which requires to turn the type to signed int but it was
already used as such everywhere anyway.

include/haproxy/receiver-t.h

@@ -50,7 +50,7 @@ struct rx_settings {
 	char *interface;                  /* interface name or NULL */
 	const struct netns_entry *netns;  /* network namespace of the listener*/
 	unsigned int options;             /* receiver options (RX_O_*) */
-	uint shards;                      /* number of shards */
+	int shards;                       /* number of shards, 0=not set yet, -1="by-thread" */
 };
 
 /* This describes a receiver with all its characteristics (address, options, etc) */

src/cfgparse.c

@@ -2972,6 +2972,10 @@ init_proxies_list_stage1:
 				shards = bind_conf->settings.shards;
 				todo = thread_set_count(&bind_conf->thread_set);
 
+				/* special values: -1 = "by-thread" */
+				if (shards == -1)
+					shards = todo;
+
 				/* no more shards than total threads */
 				if (shards > todo)
 					shards = todo;

src/listener.c

@@ -1865,7 +1865,7 @@ static int bind_parse_shards(char **args, int cur_arg, struct proxy *px, struct
 	}
 
 	if (strcmp(args[cur_arg + 1], "by-thread") == 0) {
-		val = MAX_THREADS; /* will be trimmed later anyway */
+		val = -1; /* -1 = "by-thread", will be fixed in check_config_validity() */
 	} else {
 		val = atol(args[cur_arg + 1]);
 		if (val < 1 || val > MAX_THREADS) {