Switch to using 0 instead of NULL for a void* -> int cast am: 4f98785e4d am: 0466ec5978 am: 824590ace9 am: 85c423894f am: d84d135514

Original change: https://android-review.googlesource.com/c/platform/system/memory/libion/+/1362817

Change-Id: I99d7a120bea94de20c563d4a286e20705aba3557