all: add Google Cloud Build config

Change-Id: Ibfbde783590860195122ac39f6de2a8caa8d1d01
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/2287
Reviewed-by: Marcel van Lohuizen <mpvl@google.com>
diff --git a/cloudbuild.yaml b/cloudbuild.yaml
new file mode 100644
index 0000000..1eb37e4
--- /dev/null
+++ b/cloudbuild.yaml
@@ -0,0 +1,4 @@
+steps:
+- name: golang:1.12
+  env: ['GO111MODULE=on']
+  args: ['go', 'test', './...']
\ No newline at end of file