[4.0] 8e3f919 dont use VSL_Error as a format string

[Nils Goroll]

commit 8e3f91928d66ad972c68af18e0b752b08625698e
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Tue Jul 14 17:34:38 2015 +0200

    dont use VSL_Error as a format string

diff --git a/bin/varnishtest/vtc_logexp.c b/bin/varnishtest/vtc_logexp.c
index 8f2a93e..8dc2ace 100644
--- a/bin/varnishtest/vtc_logexp.c
+++ b/bin/varnishtest/vtc_logexp.c
@@ -597,7 +597,7 @@ cmd_logexp(CMD_ARGS)
 					av++;
 					continue;
 				}
-				vtc_log(le->vl, 0, VSL_Error(le->vsl));
+				vtc_log(le->vl, 0, "%s", VSL_Error(le->vsl));
 				return;
 			}
 			vtc_log(le->vl, 0, "Unknown logexp argument: %s", *av);