Fix a buglet in handling non-ascii strings in VCL, now that we (I)

have decided what the strategy is going to be for synthetic in
the future.

Fixes	#545

bin/varnishtest/tests/r00545.vtc

+varnishtest "High-bit chars"
+
+server s1 {
+	rxreq
+	txresp
+} -start
+
+varnish v1 -vcl+backend {
+	sub vcl_deliver {
+		set resp.http.foo = "";
+	}
+} -start
+
+client c1 {
+	txreq
+	rxresp
+	expect resp.http.foo == ""
+} -run

lib/libvcl/vcc_compile.c

@@ -229,7 +229,7 @@ EncString(struct vsb *sb, const char *b, const char *e, int mode)
 			if (isgraph(*b))
 				VSB_printf(sb, "%c", *b);
 			else
-				VSB_printf(sb, "\\%03o", *b);
+				VSB_printf(sb, "\\%03o", (uint8_t)*b);
 			break;
 		}
 	}
@@ -241,7 +241,7 @@ EncToken(struct vsb *sb, const struct token *t)
 {
 
 	assert(t->tok == CSTR);
-	EncString(sb, t->dec, NULL, 0);
+	EncString(sb, t->dec, NULL, 1);
 }
 
 /*--------------------------------------------------------------------