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

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

Change-Id: I375e63b4b18f4832f19a591216b21118a4084ac7