BUG/MINOR: resolvers: return the correct value in resolvers_finalize_config()

Patch c31577f ("MEDIUM: resolvers: continue startup if network is
unavailable") was not working correctly. Indeed
resolvers_finalize_config() was returning a ERR type, but a postparser
is supposed to return 0 or 1.

The return value was never right, however it was only a problem since c31577f.

Must be backported in every stable branch.
diff --git a/src/resolvers.c b/src/resolvers.c
index f325f39..2124df7 100644
--- a/src/resolvers.c
+++ b/src/resolvers.c
@@ -2481,7 +2481,7 @@
 
 /* Finalizes the DNS configuration by allocating required resources and checking
  * live parameters.
- * Returns 0 on success, ERR_* flags otherwise.
+ * Returns 0 on success, 1 on error.
  */
 static int resolvers_finalize_config(void)
 {
@@ -2594,11 +2594,11 @@
 		goto err;
 
 	leave_resolver_code();
-	return err_code;
+	return 0;
   err:
 	leave_resolver_code();
 	resolvers_deinit();
-	return err_code;
+	return 1;
 
 }