cue/load: exclude pkg dir from tooling

Change-Id: I9786050d5d903543eb4f9ba34a8b42b8ad41f88d
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/1800
Reviewed-by: Marcel van Lohuizen <mpvl@google.com>
diff --git a/cue/load/search.go b/cue/load/search.go
index 8155593..57ab9a5 100644
--- a/cue/load/search.go
+++ b/cue/load/search.go
@@ -154,10 +154,15 @@
 		}
 	}
 
+	pkgDir := filepath.Join(root, "pkg")
+
 	filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
 		if err != nil || !fi.IsDir() {
 			return nil
 		}
+		if path == pkgDir {
+			return filepath.SkipDir
+		}
 
 		top := path == root