MEDIUM: http: The redirect strings follows the log format rules.

We handle "http-request redirect" with a log-format string now, but we
leave "redirect" unaffected.

Note that the control of the special "/" case is move from the runtime
execution to the configuration parsing. If the format rule list is
empty, the build_logline() function does nothing.
diff --git a/src/sample.c b/src/sample.c
index a4a2773..10749c0 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -901,6 +901,7 @@
 		case ARGC_HRQ: where = "in http-request header format string in"; break;
 		case ARGC_HRS: where = "in http-response header format string in"; break;
 		case ARGC_UIF: where = "in unique-id-format string in"; break;
+		case ARGC_RDR: where = "in redirect format string in"; break;
 		case ARGC_ACL: ctx = "ACL keyword"; break;
 		}