Change OWNERS of dlmalloc to the ART team am: 6664178542 am: c3be842f2f am: 495168bfcc

Original change: https://android-review.googlesource.com/c/platform/external/dlmalloc/+/2146801

Change-Id: Ia278b68700a2dc2732486ba5a76b757f158bde9a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>