Changes

On Mac and Linux, the stack traces generated by our internal debugging tools don't have very good symbol information (since they just show the results of <code>dladdr</code>). The stacks can be significantly improved (better symbols, and file name / line number information) by post-processing. Stacks can be piped through the scripts <code>mozilla/tools/rb/fix-linux-stackfix_linux_stack.plpy</code> or <code>mozilla/tools/rb/fix-macosx-stackfix_macosx_stack.py</code> to do this. These scripts are designed to be run on balance trees in addition to raw stacks; since they are rather slow, it is often '''much faster''' to generate balance trees (e.g., using <code>make-tree.pl</code> for the refcount balancer or <code>diffbloatdump.pl --use-address</code> for trace-malloc) and ''then'' run the balance trees (which are much smaller) through the post-processing.