inlined logging of uninit accesses for backward data flow

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on October 17, 2013 15:42:36_

-track_origins only shows the allocation origin.

For analyzing potential false positive uninits, I often run "-no_faspath
-verbose 3" and manually examine the log to walk backward and see where
uninit data came from.

This case covers trying to automate that by automatically logging
dataflow. We would limit to partially or fully uninit accesses. We could
also store into a circular buffer for a recent history w/o ever going to
disk.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=1351_