C++: Add defs.bzl to genproto.bzl

RELNOTES:
PiperOrigin-RevId: 258767676
Change-Id: I72c1a4b10daa62c996472b4ed03659bc2ae99d48
diff --git a/WORKSPACE b/WORKSPACE
index 4641008..79a8575 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -1,3 +1,5 @@
+workspace(name = "rules_cc")
+
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
 http_archive(