Improve logging of aborts for Android.

In Android, stderr only goes to the console, and as such will only ever
be seen by adb shell users. Since very few developers will ever actually
see that, also send the abort message to logcat and the tombstone.


git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@215983 91177308-0d34-0410-b5e6-96231b3b80d8