h2demo: add build tag

This makes it possible to pull into Google's third_party
without pulling in Camlistore and such.

h2demo/Makefile

@@ -1,5 +1,5 @@
 h2demo.linux: h2demo.go
-	GOOS=linux go build -o h2demo.linux .
+	GOOS=linux go build --tags=h2demo -o h2demo.linux .
 
 upload: h2demo.linux
 	cat h2demo.linux | go run launch.go --write_object=http2-demo-server-tls/h2demo --write_object_is_public

h2demo/h2demo.go

@@ -3,6 +3,8 @@
 // Licensed under the same terms as Go itself:
 // https://code.google.com/p/go/source/browse/LICENSE
 
+// +build h2demo
+
 package main
 
 import (