Implement the "abort" stub in assembly for ARM.

So that we can always get the full stack trace regardless of gcc's handling
of the "noreturn" attribute associated with abort().

(Cherry pick of Id264a5167e7cabbf11515fbc48f5469c527e34d4.)

Bug: 6455193

Conflicts:

	libc/Android.mk

Change-Id: I568fc5303fd1d747075ca933355f914122f94dac
3 files changed