2015: add build tags for recent talks

This should make the build green for this repository.

Updates golang/go#11811

Change-Id: I0c2300586b77733876c2311e3d27e04965c2cbf0
Reviewed-on: https://go-review.googlesource.com/18626
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/2015/gotham-grpc/backend/backend.go b/2015/gotham-grpc/backend/backend.go
index fed77e1..3381f6c 100644
--- a/2015/gotham-grpc/backend/backend.go
+++ b/2015/gotham-grpc/backend/backend.go
@@ -1,4 +1,6 @@
-// Tha backend command runs a Google server that returns fake results.
+// +build OMIT
+
+// The backend command runs a Google server that returns fake results.
 package main
 
 import (
diff --git a/2015/gotham-grpc/client/client.go b/2015/gotham-grpc/client/client.go
index da58d26..f917846 100644
--- a/2015/gotham-grpc/client/client.go
+++ b/2015/gotham-grpc/client/client.go
@@ -1,3 +1,5 @@
+// +build OMIT
+
 // The client command issues RPCs to a Google server and prints the
 // results.
 //
diff --git a/2015/gotham-grpc/frontend/frontend.go b/2015/gotham-grpc/frontend/frontend.go
index 92f6a14..4f917d4 100644
--- a/2015/gotham-grpc/frontend/frontend.go
+++ b/2015/gotham-grpc/frontend/frontend.go
@@ -1,3 +1,5 @@
+// +build OMIT
+
 // The frontend command runs a Google server that combines results
 // from multiple backends.
 package main
diff --git a/2015/gotham-grpc/search-only/search-only.pb.go b/2015/gotham-grpc/search-only/search-only.pb.go
index 548b1df..83a5bf5 100644
--- a/2015/gotham-grpc/search-only/search-only.pb.go
+++ b/2015/gotham-grpc/search-only/search-only.pb.go
@@ -2,6 +2,8 @@
 // source: search-only.proto
 // DO NOT EDIT!
 
+// +build OMIT
+
 /*
 Package search_only is a generated protocol buffer package.
 
diff --git a/2015/gotham-grpc/search/search.pb.go b/2015/gotham-grpc/search/search.pb.go
index c4e73a6..0fa9b39 100644
--- a/2015/gotham-grpc/search/search.pb.go
+++ b/2015/gotham-grpc/search/search.pb.go
@@ -2,6 +2,8 @@
 // source: search.proto
 // DO NOT EDIT!
 
+// +build OMIT
+
 /*
 Package search is a generated protocol buffer package.
 
diff --git a/2015/simplicity-is-complicated/hello.go b/2015/simplicity-is-complicated/hello.go
index 2b4d4d1..b64596e 100644
--- a/2015/simplicity-is-complicated/hello.go
+++ b/2015/simplicity-is-complicated/hello.go
@@ -1,3 +1,5 @@
+// +build OMIT
+
 package main
 
 import (
diff --git a/2015/simplicity-is-complicated/shift.go b/2015/simplicity-is-complicated/shift.go
index 0b6013c..95832de 100644
--- a/2015/simplicity-is-complicated/shift.go
+++ b/2015/simplicity-is-complicated/shift.go
@@ -1,3 +1,5 @@
+// +build OMIT
+
 package main
 
 import "fmt"