Don't use memcpy when copying mirror::Object. am: 93a10a4801

Original change: https://android-review.googlesource.com/c/platform/art/+/2476752

Change-Id: Ib8a22ed12120335591410af70dc342bd7a8f6e31
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>