[bloaty] Explicitly close StdoutPipe()

Change-Id: If938712bacb79c1adbc896b99f4b74384475907e
diff --git a/bloaty/bloaty.go b/bloaty/bloaty.go
index 16af3d0..9229af6 100644
--- a/bloaty/bloaty.go
+++ b/bloaty/bloaty.go
@@ -51,6 +51,8 @@
 	}
 	cmd := exec.Command(bloatyPath, args...)
 	stdout, err := cmd.StdoutPipe()
+	defer stdout.Close()
+
 	if err != nil {
 		out <- bloatyOutput{err: fmt.Errorf("pipe: %s: %s", file, err)}
 		return