Constify a couple of strings.

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@3234 d4fa192b-c00b-0410-8231-f00ffab90ce4

include/vrt.h

@@ -48,8 +48,8 @@ struct sockaddr;
 extern void *vrt_magic_string_end;
 
 struct vrt_backend_probe {
-	char		*url;
-	char		*request;
+	const char	*url;
+	const char	*request;
 	double		timeout;
 	double		interval;
 	unsigned	window;

lib/libvcl/vcc_fixed_token.c

@@ -328,8 +328,8 @@ vcl_output_lang_h(struct vsb *sb)
 	vsb_cat(sb, "extern void *vrt_magic_string_end;\n");
 	vsb_cat(sb, "\n");
 	vsb_cat(sb, "struct vrt_backend_probe {\n");
-	vsb_cat(sb, "	char		*url;\n");
-	vsb_cat(sb, "	char		*request;\n");
+	vsb_cat(sb, "	const char	*url;\n");
+	vsb_cat(sb, "	const char	*request;\n");
 	vsb_cat(sb, "	double		timeout;\n");
 	vsb_cat(sb, "	double		interval;\n");
 	vsb_cat(sb, "	unsigned	window;\n");