scudo: Shrink secondary header and cache entry size by a word on Linux. NFCI. am: 0e2ccab8b3 am: 54f0c8800f

Original change: https://android-review.googlesource.com/c/platform/external/scudo/+/1526162

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I922b7b401c0277d8c151b6d72ceef9ea660d65e0