Tests: fixed h2.t test with default host header.

The problem appeared after 0d4536093b39.

h2.t

diff --git a/h2.t b/h2.t
index 33a74c0..49c605c 100644
--- a/h2.t
+++ b/h2.t
@@ -492,7 +492,7 @@
 
 ($frame) = grep { $_->{type} eq "HEADERS" } @$frames;
 is($frame->{headers}->{':status'}, 301, 'return 301 relative - status');
-is($frame->{headers}->{'location'}, 'http://127.0.0.1:8080/',
+is($frame->{headers}->{'location'}, 'http://localhost:8080/',
 	'return 301 relative - location');
 
 # return 301 with relative URI and ':authority' request header field