Fix Out of Bounds read in TextDescriptions.cpp am: b63d4e785b am: a18815ba8d am: d8dad2770e am: 4803c5c3a5 am: e7caf5cd47

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/18993507

Change-Id: I4480a8caf35e36320c1dd467544e7acba37c5fd6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>