CLEANUP: tree-wide: use proper ERR_* return values for PRE_CHECK fcts

httpclient_precheck(), ssl_ocsp_update_precheck(), and
resolvers_create_default() functions are registered through
REGISTER_PRE_CHECK() macro to be called by haproxy during init from the
pre_check_list list. When calling functions registered in pre_check_list,
haproxy expects ERR_* return values. However those 3 functions currently
use raw return values, so we better use explicit ERR_* macros to prevent
breakage in the future if ERR_* values mapping were to change.

src/http_client.c

@@ -1343,9 +1343,9 @@ static int httpclient_precheck()
 
 	httpclient_proxy = httpclient_create_proxy("<HTTPCLIENT>");
 	if (!httpclient_proxy)
-		return 1;
+		return ERR_RETRYABLE;
 
-	return 0;
+	return ERR_NONE;
 }
 
 /* Initialize the logs for every proxy dedicated to the httpclient */

src/resolvers.c

@@ -3835,14 +3835,14 @@ int cfg_parse_resolvers(const char *file, int linenum, char **args, int kwm)
  */
 int resolvers_create_default()
 {
-	int err_code = 0;
+	int err_code = ERR_NONE;
 
 	if (global.mode & MODE_MWORKER_WAIT) /* does not create the section if in wait mode */
-		return 0;
+		return ERR_NONE;
 
 	/* if the section already exists, do nothing */
 	if (find_resolvers_by_id("default"))
-		return 0;
+		return ERR_NONE;
 
 	curr_resolvers = NULL;
 	err_code |= resolvers_new(&curr_resolvers, "default", "<internal>", 0);
@@ -3868,7 +3868,7 @@ int resolvers_create_default()
 
 	/* we never return an error there, we only try to create this section
 	 * if that's possible */
-	return 0;
+	return ERR_NONE;
 }
 
 int cfg_post_parse_resolvers()

src/ssl_ocsp.c

@@ -1357,12 +1357,12 @@ static int ssl_ocsp_update_precheck()
 	/* initialize the OCSP update dedicated httpclient */
 	httpclient_ocsp_update_px = httpclient_create_proxy("<OCSP-UPDATE>");
 	if (!httpclient_ocsp_update_px)
-		return 1;
+		return ERR_RETRYABLE;
 	httpclient_ocsp_update_px->conf.error_logformat_string = strdup(ocspupdate_log_format);
 	httpclient_ocsp_update_px->conf.logformat_string = httpclient_log_format;
 	httpclient_ocsp_update_px->options2 |= PR_O2_NOLOGNORM;
 
-	return 0;
+	return ERR_NONE;
 }
 
 /* initialize the proxy and servers for the HTTP client */