Fix typo in libartbase mem_map.h am: 999465fda7 am: 92cdc984d0

Original change: https://android-review.googlesource.com/c/platform/art/+/2460088

Change-Id: I43f1df80813250d0b89d70b0ce9db4f41538f070
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>