Add gvt

third_party/FiloSottile/gvt/README.google

diff --git a/third_party/FiloSottile/gvt/README.google b/third_party/FiloSottile/gvt/README.google
new file mode 100644
index 0000000..a3a1623
--- /dev/null
+++ b/third_party/FiloSottile/gvt/README.google
@@ -0,0 +1,4 @@
+gvt is a simple Go vendoring tool that downloads stuff to the
+"vendor" tree.
+
+URL: https://github.com/FiloSottile/gvt.git