This speeds up the debug malloc code by using the original unwinding code.
The only catch is that it has to link in the libc++ arm unwind code or
there will be crashes when attempting to unwind through libc++ compiled
code.
Bug: 16874447
(cherry picked from commit 3f7635f4906c53fa744731efc35235456b7d93bf)
Change-Id: If8a3821cdd95ed481bb496bf2daab449d13790f8