Dump backtrace on `DeleteLocalRef` failures (to debug mmap failures). am: ebf0dac3fa am: ec246a3282

Original change: https://android-review.googlesource.com/c/platform/art/+/2062289

Change-Id: I1988fc6fc7ad5fab849df3cb5cfc8b6acbb2222c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>