go.mod: initialize Go module
As a placeholder import path, use "google.golang.org/proto".
This is not a statement about the final import path for the repository.
Since we reserve the right to make breaking changes, we can change this import
path prior to release.
We simply need some import path (could be anything) so that the sub-packages
can import each other.
Change-Id: If80108438c7569c23326fd699dee3ffb582ef852
Reviewed-on: https://go-review.googlesource.com/127340
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..9aa5cf4
--- /dev/null
+++ b/go.mod
@@ -0,0 +1 @@
+module google.golang.org/proto
