x/talks/2014/static-analysis: add build tags to exclude demo source code from the build.

LGTM=adg
R=adg, adonovan
CC=golang-codereviews
https://golang.org/cl/172620043
diff --git a/2014/static-analysis/demo.go b/2014/static-analysis/demo.go
index c5195c0..af7bd2c 100644
--- a/2014/static-analysis/demo.go
+++ b/2014/static-analysis/demo.go
@@ -1,3 +1,5 @@
+// +build OMIT
+
 package main
 
 import "fmt"
diff --git a/2014/static-analysis/fib.go b/2014/static-analysis/fib.go
index f3df996..930231b 100644
--- a/2014/static-analysis/fib.go
+++ b/2014/static-analysis/fib.go
@@ -1,3 +1,5 @@
+// +build OMIT
+
 package main
 
 import "fmt"
diff --git a/2014/static-analysis/hello.go b/2014/static-analysis/hello.go
index 078ddff..b480451 100644
--- a/2014/static-analysis/hello.go
+++ b/2014/static-analysis/hello.go
@@ -1,3 +1,5 @@
+// +build OMIT
+
 package main
 
 import "fmt"
diff --git a/2014/static-analysis/template.go b/2014/static-analysis/template.go
index afcf81f..203c2a3 100644
--- a/2014/static-analysis/template.go
+++ b/2014/static-analysis/template.go
@@ -1,3 +1,5 @@
+// +build OMIT
+
 package P
 
 import "fmt"