Merge "Clarify the defines documentation further." am: 1441748956 am: 17b5bb88c1 am: 99be5217a3 am: 680dd50f95 am: 7328167974

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

Change-Id: I4df993e38f4bc32a115ce1a966fd637617dd4328
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>