Merge "libutils: better docs for sp<>::make" am: 767f264fa4 am: fb91070a83 am: 2eb2b5edbf

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1663182

Change-Id: I8c21003dbac86e0d57a4cf634f0c9b719f703e0a