go.talks: remove pkg/present placeholder

It's been a long time since the package was here.
We can remove this now.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/99070043
diff --git a/pkg/present/gone.go b/pkg/present/gone.go
deleted file mode 100644
index 9cd5027..0000000
--- a/pkg/present/gone.go
+++ /dev/null
@@ -1,4 +0,0 @@
-/*
-Package present has moved to code.google.com/p/go.tools/present.
-*/
-package present