Also simplifies the Darwin implementation of gettid, because
apparently libbacktrace had a better way of doing it.
Bug: 19517541
(cherry picked from commit 23f750b068)
Change-Id: I2f888e8ed7a2f5719973786cbcbb399a81867ee9
When doing a local unwind, do not include the frames that come
from either libunwind or libbacktrace.
Bug: 11518609
Change-Id: I0ec8d823aebbfa0903e61b16b7e5663f3fd65e78
The object hierarchy was confusing and convoluted. This removes
a lot of unnecessary code, and consolidates the BacktraceCurrent
and BacktraceThread code into BacktraceCurrent.
Change-Id: I01c8407d493712a48169df49dd3ff46db4a7c3ae
