Merge "Clarify the defines documentation further." am: 1441748956 am: 17b5bb88c1 am: 99be5217a3 am: 680dd50f95

Original change: https://android-review.googlesource.com/c/platform/bionic/+/2595593

Change-Id: Iba84135df834b49bb87e0835a0d9e3918cd88fa7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>