Add golang-x-sync-errgrp module

Test: build on build-tools branch
Bug: 137798757
Change-Id: If1b8b370fd7c09904df8c9819e5286c881b7f328
diff --git a/Android.bp b/Android.bp
new file mode 100644
index 0000000..0a6a530
--- /dev/null
+++ b/Android.bp
@@ -0,0 +1,6 @@
+// Useful utility.
+bootstrap_go_package {
+    name: "golang-x-sync-errgroup",
+    pkgPath: "golang.org/x/sync/errgroup",
+    srcs: ["errgroup/errgroup.go"],
+}