go/packages: remove unnecessary TODO

See adonovan's comment here:
https://go-review.googlesource.com/c/tools/+/146757/6/go/packages/golist.go#330

Change-Id: I7885fc1e7787c6b265be345f8622476b69d14325
Reviewed-on: https://go-review.googlesource.com/c/147447
Reviewed-by: Ian Cottrell <iancottrell@google.com>
diff --git a/go/packages/golist.go b/go/packages/golist.go
index 0e49999..56c1e29 100644
--- a/go/packages/golist.go
+++ b/go/packages/golist.go
@@ -347,7 +347,7 @@
 }
 
 func getSizes(cfg *Config) (types.Sizes, error) {
-	stdout, err := invokeGo(cfg, "env", "GOARCH") // TODO(matloob): perhaps merge this call with the roots call?
+	stdout, err := invokeGo(cfg, "env", "GOARCH")
 	if err != nil {
 		return nil, err
 	}