[ARM] __cxa_end_cleanup: avoid clobbering r4 am: c0a6edcf3b am: 00928ed8ee am: 4b96903904

Original change: https://android-review.googlesource.com/c/platform/external/libcxxabi/+/2024827

Change-Id: Ibd8610f45ae3983ee130a0ea4eb75fc9b11d8c3a