Fix tests that fail for recent linre2 versions.

Since 2020-06-01, backrefs fail if numbered higher than the highest
backref actually captured- Previously, re2 returned the empty string.

I believe that these tests will now pass for both current and earlier
versions.

src/tests/non_capture_paren.vtc

@@ -29,17 +29,17 @@ varnish v1 -vcl+backend {
 		} else {
 			set beresp.status = 999;
 		}
-		set beresp.http.sub = barbaz.sub(beresp.http.foo, "\0\1\2");
+		set beresp.http.sub = barbaz.sub(beresp.http.foo, "\0\1");
 		set beresp.http.subf = re2.sub("(?:bar)(baz)", beresp.http.foo,
-		                               "\0\1\2");
+		                               "\0\1");
 		set beresp.http.suball
-			= barbaz.suball(beresp.http.foo, "\0\1\2");
+			= barbaz.suball(beresp.http.foo, "\0\1");
 		set beresp.http.suballf
-			= re2.suball("(?:bar)(baz)", beresp.http.foo, "\0\1\2");
+			= re2.suball("(?:bar)(baz)", beresp.http.foo, "\0\1");
 		set beresp.http.extract
-			= barbaz.extract(beresp.http.foo, "\0\1\2");
+			= barbaz.extract(beresp.http.foo, "\0\1");
 		set beresp.http.extractf
-			= re2.extract("(?:bar)(baz)", beresp.http.foo, "\0\1\2");
+			= re2.extract("(?:bar)(baz)", beresp.http.foo, "\0\1");
 	}
 
 } -start

src/tests/set_extract.vtc

@@ -9,12 +9,12 @@ varnish v1 -vcl {
 	sub vcl_init {
 		new s = re2.set();
 		s.add("(.*)@([^.]*)", save=true);
-		s.add(".*", save=true);
+		s.add("(.)(.).*", save=true);
 		s.compile();
 
 		new n = re2.set();
 		n.add("(.*)@([^.]*)");
-		n.add(".*", save=true);
+		n.add("(.)(.).*", save=true);
 		n.compile();
 	}
 
@@ -72,13 +72,13 @@ client c1 {
 	expect resp.http.s-nmatches == "2"
 	expect resp.http.s-extract == ""
 	expect resp.http.s-first == "kremvax!boris"
-	expect resp.http.s-last == "!"
+	expect resp.http.s-last == "o!b"
 
 	expect resp.http.n-match == "true"
 	expect resp.http.n-n == "2"
 	expect resp.http.n-extract == ""
 	expect resp.http.n-first == ""
-	expect resp.http.n-last == "!"
+	expect resp.http.n-last == "o!b"
 } -run
 
 logexpect l1 -v v1 -d 1 -g vxid -q "VCL_Error" {