Merge "Mark scope guard as constexpr" am: 9c478a1c76 am: 0c317aca57 am: 55b157fbb5

Original change: https://android-review.googlesource.com/c/platform/system/libbase/+/1932480

Change-Id: I9af900a6436c0adac9044e0280ff28c58b3c7469