dnsmasq: fix heap overflow am: 2c415e570a am: d9b4de509f am: 35a6d0cb35

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/dnsmasq/+/13032295

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Id9816b16aa91c463cac086df03f66f4297a6f95b