Don't run formatting checker on generated bazel code

Change-Id: I2c9de0e01c85170dabefe7a9b7cbc775cd602eab
(cherry picked from commit 678767f36d933c0e9818819c5e463e0ae1175298)
diff --git a/BUILD b/BUILD
index 16ee973..6656a7a 100644
--- a/BUILD
+++ b/BUILD
@@ -99,10 +99,12 @@
 
 buildifier(
     name = "buildifier_check",
+    exclude_patterns = ["./tools/build/bazel/generate_workspace.bzl"],
     mode = "check",
 )
 
 buildifier(
     name = "buildifier_fix",
+    exclude_patterns = ["./tools/build/bazel/generate_workspace.bzl"],
     mode = "fix",
 )